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The Clinical Significance Of Freezing While Turning in Parkinson’s Disease
Abstract
Freezing of gait (FoG) in people with Parkinson's disease (PD) is an environmentally sensitive, intermittent problem that occurs most often during turning. FoG is difficult for clinicians to evaluate and treat because it can be difficult to elicit during a clinical visit. Here, we aimed to develop a clinically valid objective measure of freezing severity during a 2-minute 360 degrees turning-in-place. Twenty-eight subjects with PD (16 freezers, FoG+, and 12 nonfreezers, FoG-) in the "off" state and 14 healthy control subjects were tested. Subjects wore 3 inertial sensors (one on each shin and one on the waist) while 1) turning in place for 2 minutes (alternating 360 degrees to the right with 360 degrees to the left) and 2) performing an Instrumented 7m Timed Up and Go test (ITUG). Performance was videotaped, and clinical severity of FoG was independently rated by two movement disorders specialists (co-authors). Turning in place consistently resulted in FoG (13 out of 16 subjects with PD) while FoG was clinically observed in only 2 subjects with PD during the ITUG test. The Freezing Ratio during the turning test was significantly correlated with the clinical ratings (ρ=0.7, p=0.003) and with score on the new freezing of gait questionnaire (ρ=0.5, p=0.03). After correcting for symptom severity (UPDRS-III), out of the 4 objective measures of the turning test (total number of turns, average turn peak speed and average turn smoothness), only the Freezing Ratio was significantly different across groups (p=0.04). Freezing can be well quantified with body-worn inertial sensors during a 2-minute turning-in-place protocol.
... In the past, we have used the Freezing Ratio, the square of the total power in the 3-8 Hz band, divided by the square of the total power in the 0.5-3 Hz band, from the antero-posterior accelerations of the lower limbs during turning in-place as a measure of FoG [11,12]. This Freezing Ratio during 360° turns was significantly associated with: (1) FoG severity assessed by two expert movement disorders neurologists on a scale from 0 (absent) to 4 (needing assistance) and (2) FoG perception assessed by the FoG questionnaire [12]. ...
... In the past, we have used the Freezing Ratio, the square of the total power in the 3-8 Hz band, divided by the square of the total power in the 0.5-3 Hz band, from the antero-posterior accelerations of the lower limbs during turning in-place as a measure of FoG [11,12]. This Freezing Ratio during 360° turns was significantly associated with: (1) FoG severity assessed by two expert movement disorders neurologists on a scale from 0 (absent) to 4 (needing assistance) and (2) FoG perception assessed by the FoG questionnaire [12]. However, other groups have noted that the Freezing Ratio is not sensitive to akinetic periods of FoG [13]. ...
... Currently, clinical care and research divides PD subjects into freezers and non-freezers. However, the Freezing Ratio for people with PD not reporting FoG was in between the values of the healthy controls and the people reporting FoG [12]. We hypothesize that FoG is not one of two, clearly distinct states, present or absent, but rather FoG consists of a continuum of severity across the clinical course of PD. ...
Over the course of the disease, freezing of gait (FoG) will gradually impact over 80% of people with Parkinson’s disease (PD). Clinical decision-making and research design are often based on classification of patients as ‘freezers’ or ‘non-freezers’. We derived an objective measure of FoG severity from inertial sensors on the legs to examine the continuum of FoG from absent to possible and severe in people with PD and in healthy controls. One hundred and forty-seven people with PD (Off-medication) and 83 healthy control subjects turned 360° in-place for 1 minute while wearing three wearable sensors used to calculate a novel Freezing Index. People with PD were classified as: ‘definite freezers’, new FoG questionnaire (NFOGQ) score > 0 and clinically observed FoG; ‘non-freezers’, NFOGQ = 0 and no clinically observed FoG; and ‘possible freezers’, either NFOGQ > 0 but no FoG observed or NFOGQ = 0 but FoG observed. Linear mixed models were used to investigate differences in participant characteristics among groups. The Freezing Index significantly increased from healthy controls to non-freezers to possible freezers and to definite freezers and showed, in average, excellent test–retest reliability (ICC = 0.89). Unlike the Freezing Index, sway, gait and turning impairments were similar across non-freezers, possible and definite freezers. The Freezing Index was significantly related to NFOG-Q, disease duration, severity, balance confidence, and the SCOPA-Cog (p < 0.01). An increase in the Freezing Index, objectively assessed with wearable sensors during a turning- in-place test, may help identify prodromal FoG in people with PD prior to clinically-observable or patient-perceived freezing. Future work should follow objective measures of FoG longitudinally.
... Freezing of gait (FOG) is one of the most disabling features of Parkinson's disease (PD) [1]. FOG motor disorder represents an intermittent failure to initiate or maintain locomotion [2]. FOG was defined in 2010, as a "brief episodic absence or marked reduction in stride progression despite the intention to walk" [3]. ...
... The volunteers were able to walk independently for 10 m and reported experiencing FOG in the prior month. FOG severity was rated using the New Freezing of Gait Questionnaire (new FOG-Q) [1,2,5,27,31,32]. All the participants had a FOG history with different severity and frequency [20]. ...
... All subjects were assessed first in the morning in the OFF-medication state, which is at least 12 h since the last intake of dopaminergic medication, then after data collection, they took their first dose of dopaminergic medication of the day and the experiment was repeated after 40-50 min, at the ON-medication stage [4,13,27,32]. Clinical data to rate severity of PD, as the MDS-UPDRS and the Hoehn and Yahr Scale, were collected during the OFF and ON states [2,4,32]. ...
Freezing of gait (FOG), one of the most disabling features of Parkinson’s disease (PD), is a brief episodic absence or marked reduction in stride progression despite the intention to walk. Progressively more people who experience FOG restrict their walking and reduce their level of physical activity. The purpose of this study is to develop and validate a physical mobility task that induces freezing of gait in a controlled environment, employing known triggers of FOG episodes according to the literature. To validate the physical mobility tasks, we recruited 10 volunteers that suffered PD-associated freezing (60.6 ± 7.29 years-old) with new FOG-Q ranging from 12 to 26. The validation of the proposed method was carried out using inertial sensors and video recordings. All subjects were assessed during the OFF and ON medication states. The total number of FOG occurrences during data collection was 144. The proposed tasks were able to trigger 120 FOG episodes, while the TUG test caused 24. The Inertial Measurement Unit (IMU) with accelerometer and gyroscope could not only detect FOG episodes but also allowed us to visualize the three types of FOG: akinesia, festination and trembling in place.
... Our current work fills the gap in two critical points. First, none of these studies included data during the turning phase; this is an important limitation as studies have shown that FoG events are very frequent during the turning phase in PD patients (Mancini et al., 2017). Second, given the variability of the patients' conditions (severity of the PD, level of medication), precise control of the clinical and medication status is necessary. ...
... The FoG-ratio was then calculated as the ratio between the square of the total power in the frequency band corresponding to freezing episodes (3-8 Hz) and the total power in the frequency band corresponding to locomotion (0.5-3 Hz). Thus, higher FoG-ratio scores indicate greater FoG severity (Mancini et al., 2017). Finally, Spearman correlation coefficient (one-tailed) was used to determine the correlation of subjective FoG measures (NFoG-Q score) with the total time of FoG during the turning task (s) and FoG-ratio. ...
... Our results demonstrated a significant correlation between subjective (NFoG-Q) and objective (FoG-ratio, and total time of FoG during turning task) FoG measures, as observed previously (Mancini et al., 2017). This result is interesting for two reasons. ...
... These tools, however, are prone to recall bias and lack sensitivity [6]. Semi-objective evaluation of FOG severity typically involves standardized tasks such as the Timed-Up and Go (TUG) [7] and 360 degree turning tasks [8] in clinical centers, with post-hoc visual analysis of video recordings serving as the gold standard for FOG assessment [9]. Nonetheless, this manual annotation process is laborintensive and time-consuming, prompting the exploration of automatic approaches leveraging machine learning (ML) and deep learning (DL) models [10]- [13]. ...
... Historically, FOG detection primarily utilized manual feature engineering with IMUs. Early methods used threshold algorithms such as the Freezing Index, which was defined as the ratio of power in the "freezing" band (3)(4)(5)(6)(7)(8) to that in the "locomotor" band (0.5-3 Hz), to differentiate FOG from non-FOG episodes [39]. Enhancements included integrating stride features, energy thresholds, and turn counts [40]- [42]. ...
Freezing of gait (FOG) is a debilitating symptom of Parkinson's disease (PD), characterized by an absence or reduction in forward movement of the legs despite the intention to walk. Detecting FOG during free-living conditions presents significant challenges, particularly when using only inertial measurement unit (IMU) data, as it must be distinguished from voluntary stopping events that also feature reduced forward movement. Influences from stress and anxiety, measurable through galvanic skin response (GSR) and electrocardiogram (ECG), may assist in distinguishing FOG from normal gait and stopping. However, no study has investigated the fusion of IMU, GSR, and ECG for FOG detection. Therefore, this study introduced two methods: a two-step approach that first identified reduced forward movement segments using a Transformer-based model with IMU data, followed by an XGBoost model classifying these segments as FOG or stopping using IMU, GSR, and ECG features; and an end-to-end approach employing a multi-stage temporal convolutional network to directly classify FOG and stopping segments from IMU, GSR, and ECG data. Results showed that the two-step approach with all data modalities achieved an average F1 score of 0.728 and F1@50 of 0.725, while the end-to-end approach scored 0.771 and 0.759, respectively. However, no significant difference was found compared to using only IMU data in both approaches (p-values: 0.466 to 0.887). In conclusion, adding physiological data does not provide a statistically significant benefit in distinguishing between FOG and stopping.
... 6 The most sensitive task appears to be performing 360 • turns with alternating directions, 14,15,18,22 even though 360 • turns did not elicit FOG in all self-reported freezers. 14,[22][23][24] Taking advantage of multiple FOGtriggers can further improve sensitivity to elicit FOG, 9 but it is currently unclear what task combination is optimal. As people with FOG often report a specific situation where they are likely to freeze more often, 25,26 the question arises whether adding a personalized task to the protocol in the patient's home would improve sensitivity. ...
... Typical for the freezer population, participants had a long disease duration (median (range) = 11 years), marked severity of PD symptoms (mean (range) MDS-UPDRS part III, OFF = 44.4 (18-76), ON = 35.6 (10-62)), severe self-reported FOG (mean (range) NFOG-Q = 20.7 (11-28)), and many had mild cognitive impairment (median (range) MoCA = 25 (17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)). At T1, the mean (SD) duration of the FOGprovoking protocol was 5.90 (3.04) minutes in OFF and 3.99 (2.01) minutes in ON (excluding breaks). ...
Plain Language Summary
Freezing of gait is a very burdensome and episodic symptom in Parkinson’s disease that is difficult to measure. Measurement of freezing is needed to determine whether someone has freezing and how severe this is, and relies on observation during a freezing-triggering protocol. However, it is unclear what protocol is sufficiently sensitive to trigger freezing in many freezers, and whether freezing can be triggered reliably at different timepoints. Here, we investigated 1) which tasks can trigger freezing-presence and freezing-severity sensitively and reliably, 2) how medication state influences this, and 3) what task combination was most reliable. Sixty-three patients with daily freezing performed several freezing-triggering tasks in their homes, both with (ON) and without (OFF) anti-Parkinsonian medication. In twenty-six patients, the measurement was repeated 5 weeks later to determine test-retest reliability. First, we found that performing 360° turns in place with a cognitive dual task was the most sensitive and reliable task to trigger FOG. Second, sensitivity and reliability were better in OFF than in ON. Third, the most reliable protocol included: the Timed-Up and Go, 360° turns in place with and without the dual task, and a doorway condition. This protocol triggered freezing in all patients in OFF and 91.9% in ON and did so reliably in 95.8% (OFF) and 84.0% (ON) of the sample. We recommend to measure freezing with this protocol in OFF + ON, which further improved reliability. However, the measurement error for freezing-severity was high, even for this optimal protocol, underscoring the need for further optimization of freezing measurement.
... Each criterion was formulated as a question and scored as "yes" or "no". [30], [31], [32], [33], [34], [35], [36], [37], [38], [39], [40], [41], [42], [43], [44], [45], [46], [47], [48], [49], [50], [51], [52], [53], [54], [55], [56], [57], [58], [59], [60], [61], [62], Bradykinesi a 46 (33.3) [30], [31], [33], [34], [37], [39], [40], [41], [43], [46], [46], [47], [48], [49], [50], [51], [52], [55], [56], [59], [60], [62], [63], [64], [65], [65], [65], [66], [67], [68], [69], [70], [71], [72], [73], [74], [75], [76], [77], [78], [79], [80], [81], [82], [83], [84], [85], [86] Postural instability 11 (8) [39], [59], [76], [87], [88], [89], [90], [91] Gait disturbances 80 (58) [56], [61], [63], [84], [91], [92], [93], [94], [95], [96], [97], [98], [99], [100], [100], [101], [102], [103], [104], [105], [105], [106], [107], [108], [109], [110], [111], [112], [113], [114], [115], [116], [117], [118], [119], [120], [121], [122], [123], [124], [125], [126], [127], [128], [129], [130], [131], [132], [133], [134], [135], [136], [137], [137], [138], [138], [138], [139], [140], [141], [142], [143], [144], [145], [146], [147], [148], [149], [150], [151], [152], [153], [154], [155], [156], [157] Dyskinesia 36 (25.4) [31], [32], [33], [35], [40], [41], [43], [50], [50], [51], [55], [62], [64], [65], [67], [68], [68], [69], [72], [73], [74], [77], [79], [81], [83], [85], [86], [149], [158], [159], [160], [161] Table 5. PD motor features covered by the included studies. Note that multiple features covered per study are possible. ...
... Nevertheless, 34 studies partially considered these factors in their research, suggesting recognition of their importance. A notable number of studies (94) neglected this metric, indicating that they did not consider the long-term economic effects and user adoption of MHD-based interventions. ...
BACKGROUND
Mobile health devices (MHDs), such as wearables and smartphones, have the potential to improve the monitoring of people with Parkinson’s disease (PD) and inform timely and individualized disease management decisions.
OBJECTIVE
This paper provides an overview of the technologies behind mobile health devices MHDs and investigate their potential for sustainable management of PD.
METHODS
A literature search using PubMed, Scopus, and IEEE Xplore was performed between October 30, 2023, and November 16, 2023, for studies investigating the use of MHDs to measure PD cardinal motor features.
RESULTS
A total of 138 relevant papers drawn from 2364 papers were analyzed. MHDs have been mainly used to assess gait and bradykinesia (slowness of movements). Most studies focused on the patient outcomes, while overlooking aspects such as the integration of MHDs in healthcare workflows and sustainable viability factors (user adoption and cost-effectiveness).
CONCLUSIONS
When designing MHD-based interventions it is essential to balance the focus on immediate health benefits for PD patients with equal consideration for technology integration, cost-effectiveness, and user adoption to ensure comprehensive, impactful, and sustainable contributions of such interventions.
... To assess objective FOG related outcomes (% time frozen and FOG ratio) participants were asked to perform a one-minute turning in place task. This task has been validated for the assessment of FOG severity in a laboratory environment [26]. The instruction was to perform turns in alternating directions as fast and safely as possible for 1 minute. ...
... The outcomes computed for steady state gait were gait speed and stride length, calculated based on the detected gait events (heel-strike and toe-off) derived from the motion capture data. The FOG-related outcome measures, which were only analyzed in the subgroup with FOG were percentage (%) time frozen during the turning task rated via video [30], the NFOG-Q (total score and GI items: item 5 and 6), the FOG-score (total score and GI items: score in the section "start walking") [28] and the FOG ratio [26] during the turning task. The FOG ratio is the square of the total power in the 3-8 Hz band, which is the frequency of the trembling, divided by the square of the total power in the 0.5-3 Hz band, which is the frequency band of the movement, from the medio-lateral accelerations of the shanks during 360-degree turns in place to quantify FOG objectively. ...
Introduction
Previous studies have shown that anticipatory postural adjustments (APAs) are altered in people with Parkinson’s disease but its meaning for locomotion is less understood. This study aims to investigate the association between APAs and gait initiation, gait and freezing of gait and how a dynamic postural control challenging training may induce changes in these features.
Methods
Gait initiation was quantified using wearable sensors and subsequent straight walking was assessed via marker-based motion capture. Additionally, turning and FOG-related outcomes were measured with wearable sensors. Assessments were conducted one week before (Pre), one week after (Post) and 4 weeks after (Follow-up) completion of a training intervention (split-belt treadmill training or regular treadmill training), under single task and dual task (DT) conditions. Statistical analysis included a linear mixed model for training effects and correlation analysis between APAs and the other outcomes for Pre and Post-Pre delta.
Results
52 participants with Parkinson’s disease (22 freezers) were assessed. We found that APA size in the medio-lateral direction during DT was positively associated with gait speed (p<0.001) and stride length (p<0.001) under DT conditions at Pre. The training effect was largest for first step range of motion and was similar for both training modes. For the associations between changes after the training (pooled sample) medio-lateral APA size showed a significant positive correlation with first step range of motion (p = 0.033) only in the DT condition and for the non-freezers only.
Conclusions
The findings of this work revealed new insights into how APAs were not associated with first step characteristics and freezing and only baseline APAs during DT were related with DT gait characteristics. Training-induced changes in the size of APAs were related to training benefits in the first step ROM only in non-freezers. Based on the presented results increasing APA size through interventions might not be the ideal target for overall improvement of locomotion.
... 10 This requires video annotations, 10 which is unfeasible for routine clinical practice. From as early as 1993, clinician-rated FOG severity outcomes have been publishedsome without validity and reliability investigated, 11,12 some with only reliability, [13][14][15] and some with both validity and reliability reported. [16][17][18][19] However, none have translated to routine clinical practice, with clinicians expressing reasons of perceived impracticality and lack of usefulness. ...
... 20 It allows walking aid use, does not involve standing up from a chair, and may be more successful in triggering FOG given the larger turning angle and smaller width of the narrow-space. 14,[20][21][22]39,40 Compared to the commonly-used Timed Up and Go, 34 the FOG Severity Tool had 6.2 times the odds of eliciting FOG. 21 With the aim of providing a quick and easy-to-use clinical measure, this study is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint ...
Objectives
Existing objective assessments for freezing of gait (FOG) severity may be unwieldy for routine clinical practice. To provide an easy-to-use clinical measure, this cross-sectional study explored if time to complete the recently-validated FOG Severity Tool (or its components) could be used to reflect FOG severity.
Methods
People with Parkinson’s disease who could independently ambulate eight-metres, understand instructions, and without co-morbidities severely affecting gait were consecutively recruited from outpatient clinics. Participants were assessed with the FOG Severity Tool in a test-retest design, with time taken for each component recorded using a stopwatch during video-analysis. Validity of total FOG Severity Tool time, time taken to complete its turning and narrow-space components (i.e., Time To Navigate, TTN), and an adjusted-TTN were examined through correlations with the FOG Questionnaire, percentage of time spent with FOG, and FOG Severity Tool-Revised score. To facilitate clinical interpretation, TTN cutoff was determined using scatterplot smoothing (LOESS) regression whilst minimal important change (MIC) was calculated using predictive modelling.
Results
Thirty-five participants were included [82.9%(n=29)male; Median(IQR): age – 73.0(11.0)years; disease duration – 4.0(4.5)years]. The FOG Severity Tool time, TTN, and adjusted-TTN similarly demonstrated moderate correlations with the FOG Questionnaire and percentage-FOG, and very-high correlations with FOG Severity Tool-Revised. TTN was nonlinearly related to FOG severity such that a positive relationship was observed in the first 300-seconds, beyond which the association plateaued. MIC for TTN was 15.4-seconds reduction in timing (95%CI 3.2 to 28.7).
Conclusions
The TTN is a feasible, interpretable, and valid test of FOG severity, demonstrating strong convergent validity with the FOG Severity Tool-Revised. In busy clinical settings, TTN provides a viable alternative when use of existing objective FOG measures is (often) unfeasible.
Impact statement
Busy clinicians need easy-to-use measures. In under 300-seconds, TTN test offers this for FOG severity, with a 15.4-seconds decrease in TTN time considered minimal improvement.
... Different from straight-line walking, turning involves a series of complex motor tasks, such as forward motion deceleration, trunk rotation, and stepping redirection [2,3]. Thus, turning is considered as a more challenging motor task than straight-line walking, especially for those with walking impairments [4]. More importantly, turning is associated with an increased risk of falls and injuries [5]. ...
... Gait & Posture 101 (2023)[1][2][3][4][5][6][7] ...
Background:
Turning gait is considered as a challenging motor task. However, only few existing studies reported turning biomechanics from the aspect of foot plantar pressure.
Research question:
This study aimed to investigate turning biomechanics by studying foot plantar pressure characteristics METHODS: Twelve young male participants were involved in this experimental study. They were instructed to perform turning tasks with different turning angles (i.e., 30°, 60°, and 90°). Foot plantar pressure was quantified by the force time integral (FTI) underneath seven plantar sub-areas. Analysis was carried out for different turning strategies (spin turns versus step turns), separately.
Results:
The results showed that for small-angle spin turns, plantar pressure patterns changed at the early stage of the approaching step, suggesting a preparatory action for the increased lower limb range of motion in the transverse plane during turning; for step turns, an imbalance weight bearing mechanism was adopted when making large-angle turns to compensate for the centripetal force during turning.
Significance:
The findings provide improved knowledge about turning biomechanics. They have practical implications for motion planning of lower-limb assistive devices for those with difficulties in turning.
... We calculated the percentage change in the FoG Index during turning in place using cues (open and closedloop independently) relative to baseline. The FoG Index is a validated measure of FoG (Mancini et al., 2017) in the laboratory and reflects freezing severity. It is calculated as the power spectral density ratio between high (3-8 Hz) and low (0-3 Hz) frequencies of anteroposterior shin accelerations (Mancini et al., 2017). ...
... The FoG Index is a validated measure of FoG (Mancini et al., 2017) in the laboratory and reflects freezing severity. It is calculated as the power spectral density ratio between high (3-8 Hz) and low (0-3 Hz) frequencies of anteroposterior shin accelerations (Mancini et al., 2017). ...
We previously showed that both open-loop (beat of a metronome) and closed-loop (phase-dependent tactile feedback) cueing may be similarly effective in reducing Freezing of Gait (FoG), assessed with a quantitative FoG Index, while turning in place in the laboratory in a group of people with Parkinson’s disease (PD). Despite the similar changes on the FoG Index, it is not known whether both cueing responses require attentional control, which would explain FoG Index improvement. The mechanisms underlying cueing responses are poorly understood. Here, we tested the hypothesis that the salience network would predict responsiveness (i.e., FoG Index improvement) to open-loop and closed-loop cueing in people with and without FoG of PD, as salience network contributes to tasks requiring attention to external stimuli in healthy adults. Thirteen people with PD with high-quality imaging data were analyzed to characterize relationships between resting-state MRI functional connectivity and responses to cues. The interaction of the salience network and retrosplenial-temporal networks was the best predictor of responsiveness to open-loop cueing, presenting the largest effect size (d=1.16). The interaction between the salience network and subcortical as well as cingulo-parietal and subcortical networks were the strongest predictors of responsiveness to closed-loop cueing, presenting the largest effect sizes (d=1.06 and d=0.84, respectively). Salience network activity was a common predictor of responsiveness to both cueing, which suggests that auditory and proprioceptive stimuli during turning may require some level of cognitive and insular activity, anchored within the salience network, which explain FoG Index improvements in people with PD.
... Mancini et al. [32] reported that as FOG severity increases in freezers, the ability to coordinate natural movement and normal gait patterns might be impaired along with increased FOG rate and asymmetric steps during turning. These results suggest that FOG symptoms are related to the degeneration of the spinal cord pattern generator rather than the frontal cortex, including the motor cortex and supplementary motor area [32]. ...
... Mancini et al. [32] reported that as FOG severity increases in freezers, the ability to coordinate natural movement and normal gait patterns might be impaired along with increased FOG rate and asymmetric steps during turning. These results suggest that FOG symptoms are related to the degeneration of the spinal cord pattern generator rather than the frontal cortex, including the motor cortex and supplementary motor area [32]. Therefore, the results of our study on the association between NFOGQ score and turning characteristics of the direction according to the influence of unilateral motor symptoms within freezers may be helpful for early diagnosis and prediction studies according to the severity of FOG. ...
For people with Parkinson's disease (PD) with freezing of gait (FOG) (freezers), symptoms mainly exhibit as unilateral motor impairments that may cause difficulty during postural transitions such as turning during daily activities. We investigated the turning characteristics that distinguished freezers among people with PD and analyzed the association between the New Freezing of Gait Questionnaire (NFOGQ) scores and the gait characteristics according to the turning direction for the affected limbs of freezers. The study recruited 57 people with PD (27 freezers, 30 non-freezers). All experiments measured the maximum 180° turning task with the "Off" medication state. Results revealed that the outer ankle range of motion in the direction of the inner step of the more affected limb (IMA) was identified to distinguish freezers and non-freezers (RN2 = 0.735). In addition, higher NFOGQ scores were associated with a more significant anteroposterior root mean square distance of the center of mass in the IMA direction and a greater inner stance phase in the outer step of the more affected limb (OMA) direction; explanatory power was 50.1%. Assessing the maximum speed and turning direction is useful for evaluating the differences in turning characteristics between freezers and non-freezers, which can help define freezers more accurately.
... FOG-severity was evaluated as a secondary outcome in the group of freezers only by calculating: (1) the FOG-score during walking in a FOG-provoking protocol, 28 (2) the percentage of time frozen, 26 and (3) the FOG-ratio (mediolateral) 29 during the 360 turning test. ...
... However, turning is deemed a complex task requiring visual guidance, extensive sensory integration, and head-pelvis dissociation. 29 Because turning on the spot does not capture a shift from straight-line walking to asymmetrical gait, it may have been too dissimilar as a near or far marker of transfer. ...
Background: Gait deficits in people with Parkinson's disease (PD) are triggered by circumstances requiring gait adaptation. The effects of gait adaptation training on a split-belt treadmill (SBT) are unknown in PD.
Objective: We investigated the effects of repeated SBT versus tied-belt treadmill (TBT) training on retention and automaticity of gait adaptation and its transfer to over-ground walking and turning.
Methods: We recruited 52 individuals with PD, of whom 22 were freezers, in a multi-center randomized single-blind controlled study. Training consisted of 4 weeks of supervised treadmill training delivered three times per week. Tests were conducted pre- and post-training and at 4-weeks follow-up. Turning (primary outcome) and gait were assessed over-ground and during a gait adaptation protocol on the treadmill. All tasks were performed with and without a cognitive task.
Results: We found that SBT-training improved gait adaptation with moderate to large effects sizes (P < 0.02) compared to TBT, effects that were sustained at follow-up and during dual tasking. However, better gait adaptation did not transfer to over-ground turning speed. In both SBT- and TBT-arms, over-ground walking and Movement Disorder Society-Unified Parkinson's Disease Rating Scale III (MDS-UPDRS-III scores were improved, the latter of which reached clinically meaningful effects in the SBT-group only. No impact was found on freezing of gait.
Conclusion: People with PD are able to learn and retain the ability to overcome asymmetric gait-speed perturbations on a treadmill remarkably well, but seem unable to generalize these skills to asymmetric gait off-treadmill. Future study is warranted into gait adaptation training to boost the transfer of complex walking skills.
... While encouraging, the observations above are limited to forward stepping. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher [14,15]. We therefore aimed to explore the efficacy of using a weight-shifting strategy to promote successful recovery following FOG during turning. ...
... This expands findings by Maslivec et al. [13] who showed the effectiveness of similar internally generated weight-shift strategies during forward stepping tasks. Turning -a known trigger of freezing [14,15] -is a more complex task due to the added complexities of co-ordinating the position of the centre of mass over the changing base of support while simultaneously rotating body segments. Our results suggest that the simple cha-cha weight-shifting cue can enhance turning without compromising safety, neither during the laboratory-based assessment nor during subsequent self-reported use in daily life. ...
Freezing of gait (FOG) can severely compromise daily functioning in people with Parkinson’s disease. Inability to initiate a step from FOG is likely underpinned, at least in part, by a deficient preparatory weight-shift. Conscious attempts to weight-shift in preparation to step can improve success of initiating forward steps following FOG. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher. We explored the effectiveness of a dance-based (‘cha-cha’) weight-shifting strategy to re-initiate stepping following FOG during turning. Results suggest that this simple movement strategy can enhance turning steps following FOG, without compromising safety.
... We also collect sway in the medio-lateral plane as it is important for fall prevention, and we include perturbation tasks to challenge stability (see sections Dynamic Posturography on the Neurocom System and Selected Mini-BESTest Items, Two-Minute Walk Test, and a 360-Degrees Turning in Place With Opal Sensors below). Finally, our assessment captures straight walking and turning (see section Selected Mini-BESTest Items, Two-Minute Walk Test, and a 360-Degrees Turning in Place With Opal Sensors below) for overall clinical relevance, and because a subset of patients with PSP have freezing of gait. Figure 1 shows our comprehensive balance assessment protocol for PSP: the Sensory Organization Test (SOT) and Motor Control Test (MCT) with forward platform translation and toes-up perturbations on a Neurocom Balance Manager system, anticipatory postural adjustments, reactive postural control and sensory orientation aspects of the mini-BESTest (17), a two-minute walk test (23,24), and a 360-degree turning in place task (25). The mini-BESTest, two-minute walk, and 360degree turning task are all performed while wearing six Opal inertial measurement sensors (APDM Wearable Technologies, Portland, OR) (26). ...
... Both average and variability are reported. For the separate instrumented 360 degrees turning in place task, subjects are instructed to turn in place for a total of 1 min, 360 degrees to the right, then 360 degrees to the left (and so on) at a comfortable speed (25). This turning protocol elicits potential freezing of gait in a controlled manner. ...
Many studies have examined aspects of balance in progressive supranuclear palsy (PSP), but guidance on the feasibility of standardized objective balance assessments and balance scales in PSP is lacking. Balance tests commonly used in Parkinson's disease often cannot be easily administered or translated to PSP. Here we briefly review methodology in prior studies of balance in PSP; then we focus on feasibility by presenting our experience with objective balance assessment in PSP-Richardson syndrome and PSP-parkinsonism during a crossover rTMS intervention trial. We highlight lessons learned, safety considerations, and future approaches for objective balance assessment in PSP.
... The use of wearable technology such as inertial sensors allowed the development of the instrumented TUG (iTUG), which has been used in various studies in the past years [6] to enable analyses of the quality of the movements performed during the TUG assessment. Research using the iTUG has demonstrated the clinical relevance of sensorderived variables in predicting fall risk and diagnosing mobility impairments [6,7]. These findings highlight the importance of incorporating inertial sensor-based analyses into mobility assessments, providing a strong rationale for extending their application to the L-test. ...
The L-test is a performance-based measure to assess balance and mobility. Currently, the primary outcome from this test is the time required to finish it. In this study we present the instrumented L-test (iL-test), an L-test wherein mobility is evaluated by means of a wearable inertial sensor worn at the lower back. We analyzed data from 113 people across seven cohorts: healthy adults, chronic obstructive pulmonary disease, multiple sclerosis, congestive heart failure, Parkinson’s disease, proximal femoral fracture, and transfemoral amputation. The iL-test automatic segmentation was validated using stereophotogrammetry. Univariate and multivariate analyses were performed on 164 kinematic features derived from inertial signals to identify distinct patterns across different cohorts. The iL-test accurately recognized and segmented activities during the L-test for all cohorts (technical validity). A random forest classifier revealed that proximal femoral fracture and transfemoral amputation induced significantly different mobility patterns compared to healthy people with AUC values of 0.89 and 0.99, respectively. Strong correlations were found between kinematic features and clinical scores in multiple sclerosis, congestive heart failure, proximal femoral fracture, and transfemoral amputation, with consistent patterns of decreased movement ranges and smoothness with increasing disease severity. Furthermore, features derived from 90° and 180° turns were found to be important contributors to differentiation amongst cohorts, underscoring the need to evaluate different turn degrees and directions. This study emphasizes the iL-test potential to deliver automated mobility assessment across a wide range of clinical conditions, indicating a prospective avenue for improved mobility assessment and, eventually, more informed healthcare interventions.
... The inclusion of 360 • turns in narrow spaces in Segment 2 is particularly challenging for patients with PD, as this task demands a high level of balance control and coordination. Compared to 90 • or 180 • turns used in other tests, 360 • turns present a more complex challenge, further aiding in the detection of balance impairments and providing a more accurate assessment of functional mobility in this population [75,76]. ...
Background/Objectives: Parkinson's disease (PD) is a neurodegenerative disorder that significantly impairs motor function, leading to mobility challenges and an increased risk of falls. Current assessment tools often inadequately measure the complexities of motor impairments associated with PD, highlighting the need for a reliable tool. This study introduces the Motor Assessment Timed Test (MATT), designed to assess functional mobility in PD patients. Methods: A cross-sectional study was conducted involving 57 participants (38 men and 19 women) aged 44 to 84, diagnosed with idiopathic PD. Participants were recruited from three PD associations and underwent a series of assessments, including MATT, to evaluate gait, balance, and dual-task performance under conditions that reflect real-life challenges faced by individuals with PD. Results: MATT demonstrated excellent reliability with intra-rater reliability (ICC = 0.99), inter-rater reliability (ICC = 0.96-0.99), and test-retest reliability (ICC = 0.93-0.99). The coefficient of variation for total time and each segment ranged from 4.73% to 13.71%, indicating consistent performance across trials. The concurrent validity showed very high correlations with established tools such as the Timed Up and Go (TUG) test (ρ = 0.86, p < 0.001) and the Berg Balance Scale (BBS) (ρ = −0.83, p < 0.001), among others. Only 7.3% of participants reported difficulties in understanding the MATT, predominantly those in advanced stages of the disease. In addition, 23.6% of participants experienced significant challenges in performing the test, particularly individuals with lower Mini-Mental State Examination (MMSE) scores (≤ 26) and more advanced disease progression. Conclusions: MATT is a promising tool for assessing motor complications in PD, offering a comprehensive evaluation of functional mobility. Its implementation in clinical practice could enhance the management of PD, facilitating tailored interventions and improving patient outcomes.
... Accelerometers or IMUs could be placed on limbs if there is suspicion of musculoskeletal or neurological problems. In addition, some signs of disease such as freezing of gait in patients with Parkinson's disease are infrequent enough that they will not occur during an appointment [46]. However, recordings over a long period of time can pick up on this. ...
In recent years, there has been substantial work in low-cost medical diagnostics based on the physical manifestations of disease. This is due to advancements in data analysis techniques and classification algorithms and the increased availability of computing power through smart devices. Smartphones and their ability to interface with simple sensors such as inertial measurement units (IMUs), microphones, piezoelectric sensors, etc., or with convenient attachments such as lenses have revolutionized the ability collect medically relevant data easily. Even if the data has relatively low resolution or signal to noise ratio, newer algorithms have made it possible to identify disease with this data. Many low-cost diagnostic tools have been created in medical fields spanning from neurology to dermatology to obstetrics. These tools are particularly useful in low-resource areas where access to expensive diagnostic equipment may not be possible. The ultimate goal would be the creation of a “diagnostic toolkit” consisting of a smartphone and a set of sensors and attachments that can be used to screen for a wide set of diseases in a community healthcare setting. However, there are a few concerns that still need to be overcome in low-cost diagnostics: lack of incentives to bring these devices to market, algorithmic bias, “black box” nature of the algorithms, and data storage/transfer concerns.
... For participants with no annotated FOG episodes, sensitivity was then considered to be 100% before the mean and standard deviation for sensitivity were calculated. The use of multiple sensors or multiple devices [17,20,[23][24] also has a disadvantage in that they may increase power consumption and the inconvenience of daily charging if used in a home environment. In comparison, a small user-friendly single device with fewer sensors could improve compliance by improving comfort, convenience and battery life for long-term remote applications. ...
italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Objective:
Freezing of Gait (FOG) often described as the sensation of “the feet being glued to the ground” is prevalent in people with Parkinson's disease (PD) and severely disturbs mobility. In addition to tracking disease progression, precise detection of the exact boundaries for each FOG episode may enable new technologies capable of “breaking” FOG in real time. This study investigates the limits of sensitivity and performance for automatic device-based FOG detection.
Methods:
Eight machine-learning classifiers (including Neural Networks, Ensemble & Support Vector Machine) were developed using (i) accelerometer and (ii) accelerometer and gyroscope data from a waist-worn device. While wearing the device, 107 people with PD completed a walking and mobility task designed to elicit FOG. Two clinicians independently annotated the precise FOG episodes using synchronized video according to international guidelines, which were incorporated into a flowchart algorithm developed for this study. Device-detected FOG episodes were compared to the annotated FOG episodes using 10-fold cross-validation to determine accuracy and with Interclass Correlation Coefficients (ICC) to assess level of agreement.
Results:
Development used 50,962 windows of data representing over 10 hours of data and annotated activities. Very strong agreement between clinicians for precise FOG episodes was observed (90% sensitivity, 92% specificity and ICC
1,1
= 0.97 for total FOG duration). Device-based performance varied by method, complexity and cost matrix. The Neural Network that used only 67 accelerometer features provided a good balance between high sensitivity to FOG (89% sensitivity, 81% specificity and ICC
1,1
= 0.83) and solution stability (validation loss ≤ 5%).
Conclusion:
The waist-worn device consistently reported accurate detection of precise FOG episodes and compared well to more complex systems. The superior agreement between clinicians indicates there is room to improve future device-based FOG detection by using larger and more varied data sets.
Significance:
This study has clinical implications with regard to improving PD care by reducing reliance on clinical FOG assessments and time-consuming visual inspection. It shows high sensitivity to automatically detect FOG is possible.
... A second limitation of the study is the absence of an objective measurement of FoG using motion sensors. Research is ongoing to determine the best algorithm for an automatic detection of FoG [40], and algorithm for FoG evaluation directly from the APDM were also reported [41]. Nevertheless, this phenomenon exhibits a great variability during a single clinical assessment, and at the current time reliable software with automated home analysis is not yet available [42,43]. ...
Background
Gait issues, including reduced speed, stride length and freezing of gait (FoG), are disabling in advanced phases of Parkinson’s disease (PD), and their treatment is challenging. Levodopa/carbidopa intestinal gel (LCIG) can improve these symptoms in PD patients with suboptimal control of motor fluctuations, but it is unclear if continuous dopaminergic stimulation can further improve gait issues, independently from reducing Off-time.
Objective
To analyze before (T0) and after 3 (T1) and 6 (T2) months of LCIG initiation: a) the objective improvement of gait and balance; b) the improvement of FoG severity; c) the improvement of motor complications and their correlation with changes in gait parameters and FoG severity.
Methods
This prospective, longitudinal 6-months study analyzed quantitative gait parameters using wearable inertial sensors, FoG with the New Freezing of Gait Questionnaire (NFoG-Q), and motor complications, as per the MDS-UPDRS part IV scores.
Results
Gait speed and stride length increased and duration of Timed up and Go and of sit-to-stand transition was significantly reduced comparing T0 with T2, but not between T0-T1. NFoG-Q score decreased significantly from 19.3±4.6 (T0) to 11.8±7.9 (T1) and 8.4±7.6 (T2) (T1-T0 p = 0.018; T2-T0 p < 0.001). Improvement of MDS-UPDRS-IV (T0-T2, p = 0.002, T0-T1 p = 0.024) was not correlated with improvement of gait parameters and NFoG-Q from T0 to T2. LEDD did not change significantly after LCIG initiation.
Conclusion
Continuous dopaminergic stimulation provided by LCIG infusion progressively ameliorates gait and alleviates FoG in PD patients over time, independently from improvement of motor fluctuations and without increase of daily dosage of dopaminergic therapy.
... FOG severity using the FOG-ratio during a 2-min turning task, as previously published [34]. ...
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MLR) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here, we hypothesized that MLR activity during step initiation would explain the loss of PSI during APAs for step initiation in FOG (freezers). Freezers (n = 34) were assessed in the ON-medication state. We assessed the beta of blood oxygenation level-dependent signal change of areas known to initiate and pace gait (e.g., MLR) during a functional magnetic resonance imaging protocol of an APA task. In addition, we assessed the PSI of the soleus muscle during APA for step initiation, and clinical (e.g., disease duration) and behavioral (e.g., FOG severity and APA amplitude for step initiation) variables. A linear multiple regression model showed that MLR activity (R2 = 0.32, p = 0.0006) and APA amplitude (R2 = 0.13, p = 0.0097) explained together 45% of the loss of PSI during step initiation in freezers. Decreased MLR activity during a simulated APA task is related to a higher loss of PSI during APA for step initiation. Deficits in central and spinal inhibitions during APA may be related to FOG pathophysiology.
... To objectively assess FOG severity, PD patients are asked to perform brief and standardized FOG-provoking tasks in clinical centers. Common tasks include timed-up-and-go (TUG) [16], 180 or 360 degrees turning while walking [17], and 360-degree turning-in-place (360Turn) [18]. The TUG is commonly used in clinical practice since the task includes typical everyday motor tasks such as standing, walking, turning, and sitting. ...
Background
Freezing of gait (FOG) is an episodic and highly disabling symptom of Parkinson’s Disease (PD). Traditionally, FOG assessment relies on time-consuming visual inspection of camera footage. Therefore, previous studies have proposed portable and automated solutions to annotate FOG. However, automated FOG assessment is challenging due to gait variability caused by medication effects and varying FOG-provoking tasks. Moreover, whether automated approaches can differentiate FOG from typical everyday movements, such as volitional stops, remains to be determined. To address these questions, we evaluated an automated FOG assessment model with deep learning (DL) based on inertial measurement units (IMUs). We assessed its performance trained on all standardized FOG-provoking tasks and medication states, as well as on specific tasks and medication states. Furthermore, we examined the effect of adding stopping periods on FOG detection performance.
Methods
Twelve PD patients with self-reported FOG (mean age 69.33 ± 6.02 years) completed a FOG-provoking protocol, including timed-up-and-go and 360-degree turning-in-place tasks in On/Off dopaminergic medication states with/without volitional stopping. IMUs were attached to the pelvis and both sides of the tibia and talus. A temporal convolutional network (TCN) was used to detect FOG episodes. FOG severity was quantified by the percentage of time frozen (%TF) and the number of freezing episodes (#FOG). The agreement between the model-generated outcomes and the gold standard experts’ video annotation was assessed by the intra-class correlation coefficient (ICC).
Results
For FOG assessment in trials without stopping, the agreement of our model was strong (ICC (%TF) = 0.92 [0.68, 0.98]; ICC(#FOG) = 0.95 [0.72, 0.99]). Models trained on a specific FOG-provoking task could not generalize to unseen tasks, while models trained on a specific medication state could generalize to unseen states. For assessment in trials with stopping, the agreement of our model was moderately strong (ICC (%TF) = 0.95 [0.73, 0.99]; ICC (#FOG) = 0.79 [0.46, 0.94]), but only when stopping was included in the training data.
Conclusion
A TCN trained on IMU signals allows valid FOG assessment in trials with/without stops containing different medication states and FOG-provoking tasks. These results are encouraging and enable future work investigating automated FOG assessment during everyday life.
... FOG severity using the FOG-ratio during a 2-minute turning task, as previously published [40]. APA amplitude and duration for step initiation, as previously published [7,12]. ...
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have a loss of presynaptic inhibition (PSI) during anticipatory postural adjustments (APAs) for step initiation. The mesencephalic locomotor region (MRL) has connections to the reticulospinal tract that mediates inhibitory interneurons responsible for modulating PSI and APAs. Here, we hypothesized that MLR activity during step initiation would explain the loss of PSI during APAs for step initiation in freezers. Thirty-four freezers were assessed in the ON-medication state. During a functional magnetic resonance imaging protocol of simulated APA task, we assessed beta of blood oxygenation level-dependent signal change of areas known to initiate and pace gait (e.g., MLR), in addition to PSI of the soleus muscle during APA for step initiation, and clinical (e.g., disease duration) and behavioral (e.g., FOG severity and APAs amplitude for step initiation) variables. A linear multiple regression model showed that MLR activity (R2=0.32, P=0.0006) and APA amplitude (R2=0.13, P=0.0097) explained together 45% of the loss of PSI during step initiation in freezers. Decreased MLR activity during a simulated APA task is related to a higher loss of PSI during APA for step initiation. Deficits in central and spinal inhibitions during APA may be related to FOG pathophysiology.
... One hypothesis suggested by previous studies is that FOG is caused by a delay in maximum head-pelvis separation, leading to inadequate preparation for directional changes [32,65]. Additionally, the asymmetrical stepping pattern induced by turning or the reduced ability of PwPD to adapt to a new gait pattern may also contribute to this phenomenon [73]. ...
Background: Freezing of Gait (FOG) is a motor symptom frequently observed in advanced Parkinson's disease. However, due to its paroxysmal nature and diverse presentation, assessing FOG in a clinical setting can be challenging. Before FOG can be fully investigated, it is critical that a reliable experimental setting is established in which FOG can be evoked in a standardised manner, but the efficacy of various gait tasks and triggers for eliciting FOG remains unclear.
Objectives: This study aimed to conduct a systematic review of the existing literature and evaluate the available evidence for the relationship between specific motor tasks, triggers, and FOG episodes in individuals with Parkinson's disease (PwPD).
Methods: We conducted a literature search on four online databases (PubMed, Web of Science, EMBASE, and Cochrane Library) using the keywords "Parkinson's disease," "Freezing of Gait," and "triggers." A total of 128 articles met the inclusion criteria and were included in our analysis.
Results: The review found that a wide range of gait tasks were employed in gait assessment studies on PD patients. However, three tasks (turning, dual tasking, and straight walking) were the most frequently used. Turning (28%) appears to be the most effective trigger for eliciting FOG in PwPD, followed by walking through a doorway (14%) and dual tasking (10%).
Conclusions: This review thereby supports the use of turning especially 360 degrees as a reliable trigger for FOG in PwPD. This could be beneficial to clinicians during clinical evaluations and researchers who wish to assess FOG in a laboratory environment.
... Participants were selected based on the following inclusion criteria: (1) diagnosis of idiopathic PD confirmed by a movement disorders specialist by UK Parkinson's Disease Society Brain Bank diagnostic criteria; (2) FoG confirmed by answering affirmatively item 1 of the new freezing of gait questionnaire (NFoG-Q) (Nieuwboer et al., 2009) and/or if FoG was observed during the 2-minute turning task during ON medication status (Mancini et al., 2017); (3) Hoehn and Yahr stage range 2-4; (4) Mini-Mental State Examination score (MMSE) >23 (Folstein et al., 1983); (5) absence of orthopedic or neurological disorders other than PD that might affect performance in the experimental task. The exclusion criterion was a failure to participate in all training sessions or the pre-and post-tests. ...
Perturbation-based balance training (PBT) exposes individuals to a series of sudden upright balance perturbations to improve their reactive postural responses. In this study, we aimed to evaluate the effect of a short PBT program on body balance recovery following a perturbation in individuals with freezing of gait due to Parkinson's disease. Volunteers (mean age = 64 years, SD = 10.6) were pseudorandomly assigned either to a PBT (n = 9) or to a resistance training (RT, n = 10) group. PBT was implemented through balance perturbations varying in the kind, direction, side, and magnitude of support base displacements. Both groups exercised with progressive difficulty/load activities twice a week for four weeks. Specific gains and generalization to dual-tasking and faster-than-trained support base displacements were evaluated 24 h after the end of the training, and retention was evaluated after 30 days of no training. Results showed that, compared to RT, PBT led to more stable postural responses in the 30-day retention evaluation, as indicated by decreased CoP displacement, velocity, and time to direction reversal and reduced numbers of near-falls. We found no transfer either to a dual-task or to a higher perturbation velocity. In conclusion, a training program based on diverse unpredictable balance perturbations improved the stability of reactive postural responses to those perturbations suffered during the training, without generalization to more challenging tasks.
... To objectively assess FOG severity, PD patients are asked to perform brief and standardized FOG-provoking tasks in clinical centers. Common tasks include timed-up-and-go (TUG) (16), 180 or 360 degrees turning while walking (17), and 360-degree turning-in-place (360Turn) (18). The TUG is commonly used in clinical practice since the task includes typical everyday motor tasks such as standing, walking, turning, and sitting. ...
Background:
Freezing of gait (FOG) is an episodic and highly disabling symptom of Parkinson's Disease (PD). Traditionally, FOG assessment relies on time-consuming visual inspection of camera footage. Therefore, previous studies have proposed portable and automated solutions to annotate FOG. However, automated FOG assessment is challenging due to gait variability caused by medication effects and varying FOG-provoking tasks. Moreover, whether automated approaches can differentiate FOG from typical everyday movements, such as volitional stops, remains to be determined. To address these questions, we evaluated an automated FOG assessment model with deep learning (DL) based on inertial measurement units (IMUs). We assessed its performance trained on all standardized FOG-provoking tasks and medication states, as well as on specific tasks and medication states. Furthermore, we examined the effect of adding stopping periods on FOG detection performance.
Methods:
Twelve PD patients with self-reported FOG (mean age 69.33 +/- 6.28 years) completed a FOG-provoking protocol, including timed-up-and-go and 360-degree turning-in-place tasks in On/Off dopaminergic medication states with/without volitional stopping. IMUs were attached to the pelvis and both sides of the tibia and talus. A multi-stage temporal convolutional network was developed to detect FOG episodes. FOG severity was quantified by the percentage of time frozen (%TF) and the number of freezing episodes (#FOG). The agreement between the model-generated outcomes and the gold standard experts' video annotation was assessed by the intra-class correlation coefficient (ICC).
Results:
For FOG assessment in trials without stopping, the agreement of our model was strong (ICC(%TF) = 0.92 [0.68, 0.98]; ICC(#FOG) = 0.95 [0.72, 0.99]). Models trained on a specific FOG-provoking task could not generalize to unseen tasks, while models trained on a specific medication state could generalize to unseen states. For assessment in trials with stopping, the model trained on stopping trials made fewer false positives than the model trained without stopping (ICC(%TF) = 0.95 [0.73, 0.99]; ICC(#FOG) = 0.79 [0.46, 0.94]).
Conclusion:
A DL model trained on IMU signals allows valid FOG assessment in trials with/without stops containing different medication states and FOG-provoking tasks. These results are encouraging and enable future work investigating automated FOG assessment during everyday life.
... Among the 23 studies, it was found that step speed and length as well as the number of turns were decreased, and the Center of Pressure velocity, step time variability, Knutsson score were increased. Those results usually used to indicate poor motor performance (Mancini et al., 2017;Belluscio et al., 2019;Kahya et al., 2019;Caliandro et al., 2020). However, the cortical activation of PFC, PMC, SMC, and SMA was increased or decreased during different motor and balance task. ...
Background: Neurological disorders with dyskinesia would seriously affect older people’s daily activities, which is not only associated with the degeneration or injury of the musculoskeletal or the nervous system but also associated with complex linkage between them. This study aims to review the relationship between motor performance and cortical activity of typical older neurological disorder patients with dyskinesia during walking and balance tasks.
Methods: Scopus, PubMed, and Web of Science databases were searched. Articles that described gait or balance performance and cortical activity of older Parkinson’s disease (PD), multiple sclerosis, and stroke patients using functional near-infrared spectroscopy were screened by the reviewers. A total of 23 full-text articles were included for review, following an initial yield of 377 studies.
Results: Participants were mostly PD patients, the prefrontal cortex was the favorite region of interest, and walking was the most popular test motor task, interventional studies were four. Seven studies used statistical methods to interpret the relationship between motor performance and cortical activation. The motor performance and cortical activation were simultaneously affected under difficult walking and balance task conditions. The concurrent changes of motor performance and cortical activation in reviewed studies contained the same direction change and different direction change.
Conclusion: Most of the reviewed studies reported poor motor performance and increased cortical activation of PD, stroke and multiple sclerosis older patients. The external motor performance such as step speed were analyzed only. The design and results were not comprehensive and profound. More than 5 weeks walking training or physiotherapy can contribute to motor function promotion as well as cortices activation of PD and stroke patients. Thus, further study is needed for more statistical analysis on the relationship between motor performance and activation of the motor-related cortex. More different type and program sports training intervention studies are needed to perform.
... Third, FOG was defined by FOGQ, which is a selfreported questionnaire and mainly depends on patients' subjective recall. Although FOGQ has been widely used to assess the severity of FOG and has been considered a reliable screening tool for FOG patients [28], in future studies, we would apply a more objective and quantifiable method for FOG symptom monitoring, such as 2-min 360 degrees turning in place [51]. In addition, cognitive assessments of our study were conducted under the medication "ON" state in order to minimize the effect of motor symptoms on cognition. ...
Background: Freezing of gait (FOG) is a common disabling symptom in Parkinson’s disease (PD). Cognitive impairment may contribute to FOG. Nevertheless, their correlations remain controversial. We aimed to investigate cognitive differences between PD patients with and without FOG (nFOG), explore correlations between FOG severity and cognitive performance and assess cognitive heterogeneity within the FOG patients. Methods: Seventy-four PD patients (41 FOG, 33 nFOG) and 32 healthy controls (HCs) were included. Comprehensive neuropsychological assessments testing cognitive domains of global cognition, executive function/attention, working memory, and visuospatial function were performed. Cognitive performance was compared between groups using independent t-test and ANCOVA adjusting for age, sex, education, disease duration and motor symptoms. The k-means cluster analysis was used to explore cognitive heterogeneity within the FOG group. Correlation between FOG severity and cognition were analyzed using partial correlations. Results: FOG patients showed significantly poorer performance in global cognition (MoCA, p < 0.001), frontal lobe function (FAB, p = 0.015), attention and working memory (SDMT, p < 0.001) and executive function (SIE, p = 0.038) than nFOG patients. The FOG group was divided into two clusters using the cluster analysis, of which cluster 1 exhibited worse cognition, and with older age, lower improvement rate, higher FOGQ3 score, and higher proportion of levodopa-unresponsive FOG than cluster 2. Further, in the FOG group, cognition was significantly correlated with FOG severity in MoCA (r = −0.382, p = 0.021), Stroop-C (r = 0.362, p = 0.030) and SIE (r = 0.369, p = 0.027). Conclusions: This study demonstrated that the cognitive impairments of FOG were mainly reflected by global cognition, frontal lobe function, executive function, attention and working memory. There may be heterogeneity in the cognitive impairment of FOG patients. Additionally, executive function was significantly correlated with FOG severity.
... cognitive impairment as measured by the Montreal Cognitive Assessment (MoCA, total score <26) (Marinus et al., 2011), or disorders and dysfunctions that affected balance were excluded. The FoG status of PD participants was determined by item III of the Freezing of Gait Questionnaire (FOGQ), with a score of 0 indicating PD-nFoG and a score ≥1 denoting PD-FoG (Giladi et al., 2000;Mancini et al., 2017). For HCs, individuals were eligible if they were 50-80 years (to match those with PD) and were in good health. ...
Background
Freezing of gait (FoG) is a severely disabling symptom in Parkinson’s disease (PD). The cortical mechanisms underlying FoG during locomotion tasks have rarely been investigated.Objectives
We aimed to compare the cerebral haemodynamic response during FoG-prone locomotion tasks in patients with PD and FoG (PD-FoG), patients with PD but without FoG (PD-nFoG), and healthy controls (HCs).Methods
Twelve PD-FoG patients, 10 PD-nFoG patients, and 12 HCs were included in the study. Locomotion tasks included normal stepping, normal turning and fast turning ranked as three difficulty levels based on kinematic requirements and probability of provoking FoG. During each task, we used functional near-infrared spectroscopy to capture concentration changes of oxygenated haemoglobin (ΔHBO2) and deoxygenated haemoglobin (ΔHHB) that reflected cortical activation, and recorded task performance time. The cortical regions of interest (ROIs) were prefrontal cortex (PFC), supplementary motor area (SMA), premotor cortex (PMC), and sensorimotor cortex (SMC). Intra-cortical functional connectivity during each task was estimated based on correlation of ΔHBO2 between ROIs. Two-way multivariate ANOVA with task performance time as a covariate was conducted to investigate task and group effects on cerebral haemodynamic responses of ROIs. Z statistics of z-scored connectivity between ROIs were used to determine task and group effects on functional connectivity.ResultsPD-FoG patients spent a nearly significant longer time completing locomotion tasks than PD-nFoG patients. Compared with PD-nFoG patients, they showed weaker activation (less ΔHBO2) in the PFC and PMC. Compared with HCs, they had comparable ΔHBO2 in all ROIs but more negative ΔHHB in the SMC, whereas PD-nFoG showed SMA and PMC hyperactivity but more negative ΔHHB in the SMC. With increased task difficulty, ΔHBO2 increased in each ROI except in the PFC. Regarding functional connectivity during normal stepping, PD-FoG patients showed positive and strong PFC-PMC connectivity, in contrast to the negative PFC-PMC connectivity observed in HCs. They also had greater PFC-SMC connectivity than the other groups. However, they exhibited decreased SMA-SMC connectivity when task difficulty increased and had lower SMA-PMC connectivity than HCs during fast turning.Conclusion
Insufficient compensatory cortical activation and depletion of functional connectivity during complex locomotion in PD-FoG patients could be potential mechanisms underlying FoG.Clinical trial registrationChinese clinical trial registry (URL: http://www.chictr.org.cn, registration number: ChiCTR2100042813).
... These previous findings may explain the strong association of FOG-ratio with DTC on stride length, but not with DTC on gait speed that we found here. Additionally, FOG-ratio represents a measure of 'trembling of the knees' that is the FOG hallmark Mancini et al., 2017;S. T. Moore, MacDougall, & Ondo, 2008). ...
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have difficulty initiating and maintaining a healthy gait pattern; however, the relationship among FOG severity, gait initiation, and gait automaticity, in addition to the neural substrate of this relationship has not been investigated. This study investigated the association among FOG severity during turning (FOG-ratio), gait initiation (anticipatory postural adjustment [APA]), and gait automaticity (dual-task cost [DTC]), and the neural substrates of these associations. Thirty-four individuals with FOG of PD were assessed in the ON-medication state. FOG-ratio during a turning test, gait automaticity using DTC on stride length and gait speed, and APA during an event-related functional magnetic resonance imaging protocol to assess brain activity from the regions of interest (e.g., dorsolateral prefrontal cortex [DLPFC] and mesencephalic locomotor region [MLR]) were assessed in separated days. Results showed that FOG-ratio, APA amplitude, and DTC on stride length are negatively associated among them (P < 0.05). APA amplitude and DTC on stride length explained 59% of the FOG-ratio variance (P < 0.05). Although the activity of the right DLPFC and right MLR explained 55% of the FOG-ratio variance (P < 0.05) and 30% of the DTC on stride length variance (P ≤ 0.05), only the activity of the right MLR explained 23% of the APA amplitude (P < 0.05). FOG severity during turning, APA amplitude, and stride length automaticity are associated among them and share a similar locomotor substrate, as the MLR activity was a common brain region in explaining the variance of these variables.
... Some PwPD develop freezing of gait over the course of their disease progression 17 . Along with other groups, we have shown that PwPD with freezing of gait have differences in disease and gait features outside of the actual episodes of gait freezing [18][19][20][21][22][23][24][25][26][27][28][29][30][31] . We therefore performed a subgroup analysis using the presence or absence of freezing to split groups and compare to differential results previously reported in these sub-phenotypes of PwPD. ...
Introduction: Gait, balance and cognitive impairment make travel cumbersome for People with
Parkinson’s disease (PwPD). About 75% of PwPD cared for at the University of Arkansas for
Medical Sciences’ Movement Disorders Clinic reside in medically underserved areas (MUAs).
Validated remote evaluations could help improve their access to care. Our goal was to explore
the feasibility of telemedicine research visits for evaluation of multi-modal function in PwPD in
a rural state.
Methods: In-home telemedicine research visits were performed in PwPD. Motor and non-motor
disease features were evaluated and quantified by trained personnel, digital survey instruments
for self-assessments, digital voice recordings, and scanned and digitized Archimedes spiral
drawings. Participants MUA residence was determined after evaluations were completed.
Results: Twenty of the fifty PwPD enrolled resided in MUAs. The groups were well matched for
disease duration, modified motor UPDRS, and Montreal Cognitive assessment scores but MUA
participants were younger. Ninety-two percent were satisfied with their visit and 61% were more
likely to participate in future telemedicine research. MUA participants travelled longer distances,
with higher travel costs, lower income and education level. While 50% of MUA participants
reported self-reliance for in-person visits, 85% reported self-reliance for the telemedicine visit.
We rated audio-video quality highly in approximately 60% of visits in both groups. There was
good correlation with prior in-person research assessments in a subset of participants.
Conclusions: In-home research visits for PwPD in medically underserved areas are feasible and
could help improve access to care and research participation in these traditionally
underrepresented populations.
Key words: telemedicine, health equity, rural health, ambulatory monitoring, Parkinson disease,
medically underserved area
... As outcome measures, we used the 24 objective measures that we found to be most sensitive in discriminating between people with PD and healthy controls. 24 The FoG ratio was calculated from the sensors on the shins according to methods described in Mancini et al. 29 Motor and cognitive dual task (DTC) were calculated as in our previous paper. 25 Specifically, when a dual task was added to walking, the dual cost (DC) was calculated as DC (%) = 100 × (dual-task measure-single-task measure)/single-task measure. ...
Background and Aim
Individuals with Parkinson’s disease (PD) with and without freezing of Gait (FoG) may respond differently to exercise interventions for several reasons, including disease duration. This study aimed to determine whether both people with and without FoG benefit from the Agility Boot Camp with Cognitive Challenges (ABC-C) program.
Methods
This secondary analysis of our ABC-C trial included 86 PD subjects: 44 without FoG (PD−FoG) and 42 with FoG (PD + FoG). We collected measures of standing sway balance, anticipatory postural adjustments, postural responses, and a 2-minute walk with and without a cognitive task. Two-way repeated analysis of variance, with disease duration as covariate, was used to investigate the effects of ABC-C program. Effect sizes were calculated using standardized response mean (SRM) for PD−FoG and PD + FoG, separately.
Results
The ABC-C program was effective in improving gait performance in both PD−FoG and PD + FoG, even after controlling for disease duration. Specifically, dual-task gait speed ( P < .0001), dual-cost stride length ( P = .012), and these single-task measures: arm range of motion ( P < .0001), toe-off angle ( P = .005), gait cycle duration variability ( P = .019), trunk coronal range of motion ( P = .042), and stance time ( P = .046) improved in both PD−FoG and PD + FoG. There was no interaction effect between time (before and after exercise) and group (PD−FoG/PD + FoG) in all 24 objective measures of balance and gait. Dual-task gait speed improved the most in PD + FoG (SRM = 1.01), whereas single-task arm range of motion improved the most in PD−FoG (SRM = 1.01).
Conclusion
The ABC-C program was similarly effective in improving gait (and not balance) performance in both PD−FoG and PD + FoG.
... This neuroimaging approach has been extensively used in studying the neural correlates of FoG in patients with PD as it permits the assessment of the whole brain without an experimental task. Rs-fMRI quantifies the functional connectivity between spatially disparate neural networks (intrinsic connectivity networks, ICN) by detecting fluctuations in spontaneous BOLD signals across the whole brain (Mancini et al., 2017). The parameters derived from rs-fMRI indicate a correlation (coupled) or an anti-correlation (anti-coupled) in the activity of the examined specific functional neural networks/ICNs (Biswal et al., 1995;Grayson and Fair, 2017). ...
Freezing of gait (FoG) is a paroxysmal and sporadic gait impairment that severely affects PD patients’ quality of life. This review summarizes current neuroimaging investigations that characterize the neural underpinnings of FoG in PD. The review presents and discusses the latest advances across multiple methodological domains that shed light on structural correlates, connectivity changes, and activation patterns associated with the different pathophysiological models of FoG in PD. Resting-state fMRI studies mainly report cortico-striatal decoupling and disruptions in connectivity along the dorsal stream of visuomotor processing, thus supporting the ‘interference’ and the ‘perceptual dysfunction’ models of FoG. Task-based MRI studies employing virtual reality and motor imagery paradigms reveal a disruption in functional connectivity between cortical and subcortical regions and an increased recruitment of parieto-occipital regions, thus corroborating the ‘interference’ and ‘perceptual dysfunction’ models of FoG. The main findings of fNIRS studies of actual gait primarily reveal increased recruitment of frontal areas during gait, supporting the ‘executive dysfunction’ model of FoG. Finally, we discuss how identifying the neural substrates of FoG may open new avenues to develop efficient treatment strategies.
... The new FOG-Q has recently been found to be unreliable and not responsive to small effect sizes [7]. Measures that rely on capturing a FOG episode in the laboratory (direct measures) [8][9][10][11][12] are limited by the inherent variability of each episode; therefore, a captured episode may not be representative of overall FOG severity. Furthermore, approaches to reliably trigger an episode have not been established. ...
Background
Freezing of gait (FOG) is notoriously difficult to quantify, which has led to the use of multiple markers as outcomes for clinical trials. The instrumented timed up and go (TUG) and the many parameters that can be derived from it are commonly used as objective markers of FOG severity in clinical trials; however, it is unknown if they represent actual FOG severity.
Objective
To determine the specificity and responsiveness of objective surrogate markers of FOG severity commonly utilized in FOG studies.
Methods
Study design: We compared the specificity and responsiveness of commonly used markers in FOG clinical trials. Markers compared included velocity, step/stride length, step/stride length variability, TUG, and turn duration. Data was collected in four conditions (ON and OFF dopaminergic drugs, with and without a dual task). Unified Parkinson’s Disease Rating Scale (UPDRS) was administered in the ON and OFF states.
Results
Thirty-three subjects were recruited (17 PD subjects without FOG (PD-control) and 16 subjects with PD and dopa-responsive FOG PD-FOG). The UPDRS motor scores were 24.9 for the PD-control group in the ON state, 24.8 for the FOG group in the ON state, and 42.4 for the FOG group in the OFF state. Significant mean differences between the ON and OFF conditions were observed with all surrogate markers (p < 0.01). However, only dual task turn duration and step variability showed trends toward significance when comparing PD-control and ON-FOG (p = 0.08). Test–retest reliability was high (ICC > 0.90) for all markers except standard deviations. Step length variability was the only marker to show an area under the ROC curve analysis > 0.70 comparing ON-FOG vs. PD-control.
Conclusions
Multiple candidate surrogate markers for FOG severity showed responsiveness to levodopa challenge; however, most were not specific for FOG severity.
... The SO section includes stabilometry tests on different surfaces (namely hard, soft and 30 • inclined) with both eyes-open (EO) and eyes-closed (EC) conditions and exploring both single and dualtask paradigms (DT). The DG section, instead, includes of Timed Up and Go (TUG) with and without dual-tasking to determine the effects of cognitive load on gait performance [48][49][50][51]. In the first three sections of the test, the maximum score is 6 and for the latter is 10, with a maximum total score of 28 points [47]. ...
The main objective of this study is to test the effect of thermal aquatic exercise on motor symptoms and quality of life in people with Parkinson’s Disease (PD). Fourteen participants with diagnosisofidiopathicPDcompletedthewholerehabilitationsessionandevaluationprotocol(Hoehn and Yahr in OFF state: 2–3; Mini Mental State Examination >24; stable pharmacological treatment in the 3 months prior participating in the study). Cognitive and motor status, functional abilities and qualityoflifewereassessedatbaselineandafteranintensiverehabilitationprograminthermalwater (12 sessions of 45 min in a 1.4 m depth pool at 32–36◦C). The Mini Balance Evaluation System Test (Mini-BESTest)andthePDQualityofLifeQuestionnaire(PDQ-39)wereconsideredasmainoutcomes. Secondary assessment measures evaluated motor symptoms and quality of life and psychological well-being. Participants kept good cognitive and functional status after treatment. Balance of all the participants significantly improved (Mini-BESTest: p < 0.01). The PDQ-39 significantly improved after rehabilitation (p = 0.038), with significance being driven by dimensions strongly related to motor status. Thermal aquatic exercise may represent a promising rehabilitation tool to prevent the impact of motor symptoms on daily-life activities of people with PD. PDQ-39 improvement foreshows good effects of the intervention on quality of life and psychological well-being.
... Dessa forma, vários estudos vêm sendo realizados, com intuito de revelar novos avanços na avaliação e tratamento do congelamento da marcha, devido ser um sintoma difícil para ser avaliado com precisão, por meio da observação, visto que os resultados obtidos acabam sendo subjetivos, apenas com base em relatos dos pacientes (MANCINI et al., 2017). Além disso, é um sintoma episódico e pode desaparecer durante a avaliação clínica devido a portador estar atento na sua marcha (BARTHEL et al., 2016). ...
... Dessa forma, vários estudos vêm sendo realizados, com intuito de revelar novos avanços na avaliação e tratamento do congelamento da marcha, devido ser um sintoma difícil para ser avaliado com precisão, por meio da observação, visto que os resultados obtidos acabam sendo subjetivos, apenas com base em relatos dos pacientes (MANCINI et al., 2017). Além disso, é um sintoma episódico e pode desaparecer durante a avaliação clínica devido a portador estar atento na sua marcha (BARTHEL et al., 2016). ...
Turning behaviors are affected in people with Parkinson’s disease (PwPD) leading to falls and Freezing of Gait (FOG). Levodopa therapy is commonly recommended for PwPD to help alleviate motor symptoms. Knowledge of turning dynamics with levodopa therapy is limited and could improve clinical care. We enrolled 44 PwPD already on levodopa therapy and analyzed their turns on an instrumented gait mat. Participants made 180-degree turns in their OFF-state (> 8 hours off levodopa) then ON-state (1 hour after levodopa). Thirteen turn measures were assessed for changes between the OFF to ON-state. Turns in the ON-state had faster stride-velocity, fewer steps, and trending towards lengthier turns, better foot ground contact, and decreased variability in stance-time. Regression modeling suggested greater improvement in turn stride-velocity, better foot contact, and lengthier turns with longer levodopa duration, and fewer steps and lower variability in stance-time with higher FOG severity. Our data suggests worse OFF-state function and retained levodopa responsiveness leading to larger improvement in turn measures in those on levodopa longer (or longer disease duration) and in those with levodopa unresponsive FOG. Our results provide important evidence for continued aggressive levodopa management to improve mobility during turns even in advanced Parkinson’s disease.
The mechanisms underlying Parkinson’s disease (PD) are complex and not fully understood, and the box-and-arrow model among other current models present significant challenges. This paper explores the potential role of the allocentric brain and especially its grid cells in several PD motor symptoms, including bradykinesia, kinesia paradoxa, freezing of gait, the bottleneck phenomenon, and their dependency on cueing. It is argued that central hubs, like the locus coeruleus and the pedunculopontine nucleus, often narrowly interpreted in the context of PD, play an equally important role in governing the allocentric brain as the basal ganglia. Consequently, the motor and secondary motor (e.g., spatially related) symptoms of PD linked with dopamine depletion may be more closely tied to erroneous computation by grid cells than to the basal ganglia alone. Because grid cells and their associated central hubs introduce both spatial and temporal information to the brain influencing velocity perception they may cause bradykinesia or hyperkinesia as well. In summary, PD motor symptoms may primarily be an allocentric disturbance resulting from virtual faulty computation by grid cells revealed by dopamine depletion in PD.
Background
Turning in place is a challenging motor task and is used as a brief assessment test of lower limb function and dynamic balance. This review aims to examine how research of instrumented analysis of turning in place is implemented. In addition to reporting the studied population, we covered acquisition systems, turn detection methods, quantitative parameters, and how these parameters are computed.
Methods
Following the development of a rigorous search strategy, the Web of Science and Scopus were systematically searched for studies involving the use of turning-in-place. From the selected articles, the study population, types of instruments used, turn detection method, and how the turning-in-place characteristics were calculated.
Results
Twenty-one papers met the inclusion criteria. The subject groups involved in the reviewed studies included young, middle-aged, and older adults, stroke, multiple sclerosis and Parkinson’s disease patients. Inertial measurement units (16 studies) and motion camera systems (5 studies) were employed for gathering measurement data, force platforms were rarely used (2 studies). Two studies used commercial software for turn detection, six studies referenced previously published algorithms, two studies developed a custom detector, and eight studies did not provide any details about the turn detection method. The most frequently used parameters were mean angular velocity (14 cases, 7 studies), turn duration (13 cases, 13 studies), peak angular velocity (8 cases, 8 studies), jerkiness (6 cases, 5 studies) and freezing-of-gait ratios (5 cases, 5 studies). Angular velocities were derived from sensors placed on the lower back (7 cases, 4 studies), trunk (4 cases, 2 studies), and shank (2 cases, 1 study). The rest (9 cases, 8 studies) did not report sensor placement. Calculation of the freezing-of-gait ratio was based on the acceleration of the lower limbs in all cases. Jerkiness computation employed acceleration in the medio-lateral (4 cases) and antero-posterior (1 case) direction. One study did not reported any details about jerkiness computation.
Conclusion
This review identified the capabilities of turning-in-place assessment in identifying movement differences between the various subject groups. The results, based on data acquired by inertial measurement units across studies, are comparable. A more in-depth analysis of tests developed for gait, which has been adopted in turning-in-place, is needed to examine their validity and accuracy.
Background
Freezing of Gait (FOG) is a motor symptom frequently observed in advanced Parkinson’s disease. However, due to its paroxysmal nature and diverse presentation, assessing FOG in a clinical setting can be challenging. Before FOG can be fully investigated, it is critical that a reliable experimental setting is established in which FOG can be evoked in a standardized manner, but the efficacy of various gait tasks and triggers for eliciting FOG remains unclear.
Objectives
This study aimed to conduct a systematic review of the existing literature and evaluate the available evidence for the relationship between specific motor tasks, triggers, and FOG episodes in individuals with Parkinson’s disease (PwPD).
Methods
We conducted a literature search on four online databases (PubMed, Web of Science, EMBASE, and Cochrane Library) using the keywords “Parkinson’s disease,” “Freezing of Gait”, “triggers” and “tasks”. A total of 128 articles met the inclusion criteria and were included in our analysis.
Results
The review found that a wide range of gait tasks were employed in studies assessing FOG among PD patients. However, three tasks (turning, dual tasking, and straight walking) emerged as the most frequently used. Turning (28%) appears to be the most effective trigger for eliciting FOG in PwPD, followed by walking through a doorway (14%) and dual tasking (10%).
Conclusion
This review thereby supports the utilisation of turning, especially a 360-degree turn, as a reliable trigger for FOG in PwPD. This finding could be beneficial to clinicians conducting clinical evaluations and researchers aiming to assess FOG in a laboratory environment.
Background:
The "gold standard" marker for freezing of gait severity is percentage of time spent with freezing observed through video analysis.
Objective:
This study examined inter- and intra-rater reliability and variability of physiotherapists rating freezing of gait severity through video analysis and explored the effects of experience.
Methods:
Thirty physiotherapists rated 14 videos of Timed Up and Go performance by people with Parkinson's and gait freezing. Ten videos were unique, while four were repeated. Freezing frequency, total duration, and percentage of time spent with freezing were computed. Reliability and variability were estimated using ICC (2,1) and mean absolute differences. Between-group differences were calculated with the one-way ANOVA.
Results:
Inter- and intra-rater reliability ranged from moderate to good (ICC: inter-rater frequency = 0.63, duration = 0.78, percentage = 0.50; intra-rater frequency = 0.84, duration = 0.89, percentage = 0.50). Variability for freezing frequency was two episodes. Inter- and intra-rater variability for total freezing duration was 18.8 and 12.3 seconds, respectively. For percentage of time spent with freezing, this was 15.2% and 13.5%. Physiotherapy experience had no effect.
Conclusion:
Physiotherapists demonstrated sufficient reliability, but variability was large enough to cause changes in severity classifications on existing rating scales. Percentage of time spent with freezing was the least reliable marker, supporting the use of freezing frequency or total duration instead.
Background
Freezing of gait (FOG) is a debilitating, variably expressed motor symptom in people with Parkinson’s disease (PwPD) with limited treatments.
Objective
To determine if the rate of progression in spatiotemporal gait parameters in people converting from a noFOG to a FOG phenotype (FOGConv) was faster than non-convertors, and determine if gait parameters can help predict this conversion.
Methods
PwPD were objectively monitored longitudinally, approximately every 6 months. Non-motor assessments were performed at the initial visit. Steady-state gait in the levodopa ON-state was collected using a gait mat (Protokinetics) at each visit. The rate of progression in 8 spatiotemporal gait parameters was calculated. FOG convertors (FOGConv) were classified if they did not have FOG at initial visit and developed FOG at a subsequent visit.
Results
Thirty freezers (FOG) and 30 non-freezers were monitored an average of 3.5 years, with 10 non-freezers developing FOG (FOGConv). FOGConv and FOG had faster decline in mean stride-length, swing-phase-percent, and increase in mean total-double-support percent, coefficient of variability (CV) foot-strike-length and CV swing-phase-percent than the remaining non-freezers (noFOG). On univariate modeling, progression rates of mean stride-length, stride-velocity, swing-phase-percent, total-double-support-percent and of CV swing-phase-percent had high discriminative power (AUC > 0.83) for classification of the FOGConv and noFOG groups.
Conclusion
FOGConv had a faster temporal decline in objectively quantified gait than noFOG, and progression rates of spatiotemporal gait parameters were more predictive of FOG phenotype conversion than initial (static) parameters Objectively monitoring gait in disease prediction models may help define FOG prone groups for testing putative treatments.
Objective:
We investigated changes in indices of muscle synergies prior to gait initiation and the effects of gaze shift in patients with Parkinson's disease (PD). A long-term objective of the study is to develop a method for quantitative assessment of gait-initiation problems in PD.
Methods:
PD patients without clinical signs of postural instability and two control groups (age-matched and young) performed a gait initiation task in a self-paced manner, with and without a quick prior gaze shift produced by turning the head. Muscle groups with parallel scaling of activation levels (muscle modes) were identified as factors in the muscle activation space. Synergy index stabilizing center of pressure trajectory in the anterior-posterior and medio-lateral directions (indices of stability) was quantified in the muscle mode space. A drop in the synergy index in preparation to gait initiation (anticipatory synergy adjustment, ASA) was quantified.
Results:
Compared to the control groups, PD patients showed significantly smaller synergy indices and ASA for both directions of the center of pressure shift. Both PD and age-matched controls, but not younger controls, showed detrimental effects of the prior gaze shift on the ASA indices.
Conclusions:
PD patients without clinically significant posture or gait disorders show impaired stability of the center of pressure and its diminished adjustment during gait initiation.
Significance:
The indices of stability and ASA may be useful to monitor pre-clinical gait disorders, and lower ASA may be relevant to emergence of freezing of gait in PD.
Introduction:
People with Parkinson's disease (PD) with freezing of gait (FOG; freezers) show impaired dynamic balance and experience falls more frequently compared to those without (non-freezers). Here, we explore the neural underpinnings of these freezing-related balance problems.
Methods:
12 freezers, 16 non-freezers and 14 controls performed a dynamic balance task in the lab. The next day, the same task was investigated in the MRI-scanner through motor imagery (MI). A visual imagery (VI) control task was also performed. Imagery engagement was determined by comparing the performance times between the dynamic balance task, and its MI- and VI-variants. Balance-related brain activations in regions of interest were contrasted between groups based on an MI > rest versus VI > rest contrast.
Results:
Freezers and non-freezers were matched for age, cognition and disease severity. Similar performance times between the balance control task and the MI-conditions revealed excellent imagery engagement. Compared to non-freezers, freezers showed decreased activation in regions of interest located in the left mesencephalic locomotor region (MLR; p = 0.006), right anterior cerebellum (p = 0.017) and cerebellar vermis (p < 0.001). Intriguingly, non-freezers showed higher activations in the cerebellar vermis than controls (p = 0.010).
Conclusion:
Overall, we showed that decreased activation in the left MLR, and cerebellar regions in freezers relative to non-freezers could explain why dynamic balance is more affected in freezers. As non-freezers displayed increased cerebellar vermis activation compared to controls, it is possible that freezers show an inability to recruit sufficient compensatory cerebellar activity for effective dynamic balance control.
Purpose
To summarize the effects of rehabilitation interventions to reduce freezing of gait (FOG) in people with Parkinson’s disease.
Methods
A systematic review with meta-analyses of randomized trials of rehabilitation interventions that reported a FOG outcome was conducted. Quality of included studies and certainty of FOG outcome were assessed using the PEDro scale and GRADE framework.
Results
Sixty-five studies were eligible, with 62 trialing physical therapy/exercise, and five trialing cognitive and/or behavioral therapies. All meta-analyses produced very low-certainty evidence. Physical therapy/exercise had a small effect on reducing FOG post-intervention compared to control (Hedges’ g= −0.26, 95% CI= −0.38 to −0.14, 95% prediction interval (PI)= −0.38 to −0.14). We are uncertain of the effects on FOG post-intervention when comparing: exercise with cueing to without cueing (Hedges’ g= −0.58, 95% CI= −0.86 to −0.29, 95% PI= −1.23 to 0.08); action observation training plus movement strategy practice to practice alone (Hedges’ g= −0.56, 95% CI= −1.16 to 0.05); and dance to multimodal exercises (Hedges’ g= −0.64, 95% CI= −1.53 to 0.25).
Conclusions
We are uncertain if physical therapy/exercise, cognitive or behavioral therapies, are effective at reducing FOG.
•
Implications for rehabilitation
• FOG leads to impaired mobility and falls, but the effect of rehabilitation interventions (including physical therapy/exercise and cognitive/behavioral therapies) on FOG is small and uncertain.
• Until more robust evidence is generated, clinicians should assess FOG using both self-report and physical measures, as well as other related impairments such as cognition, anxiety, and fear of falling.
• Interventions for FOG should be personalized based on the individual’s triggers and form part of a broader exercise program addressing gait, balance, and falls prevention.
• Interventions should continue over the long term and be closely monitored and adjusted as individual circumstances change.
Objectives
There is no standardisation of tasks or measures for evaluation of freezing of gait severity in people with Parkinson's disease. This study aimed to develop a clinician-rated tool for freezing of gait severity (i.e. Freezing of Gait Severity Tool), through determining clinicians’ ratings of the most important triggering circumstances to be examined and aspects of freezing of gait to be measured.
Design
A three-round, web-based Delphi study.
Participants
Healthcare professionals, with at least five years’ experience in managing freezing of gait in people with Parkinson.
Main outcome measures
Round 1 required participants ( n = 28) to rate items on a 5-point Likert scale, based on priority for inclusion in the Freezing of Gait Severity Tool. In Round 2, participants ( n = 18) ranked the items based on priority for inclusion. In Round 3, participants ( n = 18) confirmed or rejected the shortlisted items by judging their ability, on a binary scale, to screen for freezing of gait, detect changes in freezing severity, and discriminate between degrees of severity.
Results
Participants agreed with the triggering circumstances of turning hesitation, narrow space hesitation, start hesitation, cognitive dual-tasking, and open space hesitation should be assessed; and the aspects of gait freezing to be measured included freezing type, number of freezing episodes during a task, and average duration of freezing episodes.
Conclusions
This study attained a consensus for the items to be included in a clinician-rated tool for freezing of gait severity. Future studies should investigate psychometric properties and clinical feasibility of the Freezing of Gait Severity Tool.
Background:
Freezing of gait (FOG) is a complex symptom in Parkinson's disease (PD) that is both elusive to elicit and varied in its presentation. These complexities present a challenge to measuring FOG in a sensitive and reliable way, precluding therapeutic advancement.
Objective:
We investigated the reliability, validity, and responsiveness of manual video annotations of the turning-in-place task and compared it to the sensor-based FOG ratio.
Methods:
Forty-five optimally medicated people with PD and FOG performed rapid alternating 360° turns without and with an auditory stroop dual task, thrice over two consecutive days. The tasks were video recorded, and inertial sensors were placed on the lower back and shins. Interrater reliability between three raters, criterion validity with self-reported FOG, and responsiveness to single-session split-belt treadmill (SBT) training were investigated and contrasted with the sensor-based FOG ratio.
Results:
Visual ratings showed excellent agreement between raters for the percentage time frozen (%TF) (ICC [intra-class correlation coefficient] = 0.99), the median duration of a FOG episode (ICC = 0.90), and the number of FOG episodes (ICC = 0.86). Dual tasking improved the sensitivity and validity of visual FOG ratings resulting in increased FOG detection, criterion validity with self-reported FOG ratings, and responsiveness to a short SBT intervention. The sensor-based FOG ratio, on the contrary, showed complex FOG presentation-contingent relationships with visual and self-reported FOG ratings and limited responsiveness to SBT training.
Conclusions:
Manual video annotations of FOG during dual task turning in place generate reliable, valid, and sensitive outcomes for investigating therapeutic effects on FOG. © 2021 International Parkinson and Movement Disorder Society.
Freezing of gait is a common and disabling symptom in patients with parkinsonism, characterised by sudden and brief episodes of inability to produce effective forward stepping. These episodes typically occur during gait initiation or turning. Treatment is important because freezing of gait is a major risk factor for falls in parkinsonism, and a source of disability to patients. Various treatment approaches exist, including pharmacological and surgical options, as well as physiotherapy and occupational therapy, but evidence is inconclusive for many approaches, and clear treatment protocols are not available. To address this gap, we review medical and non-medical treatment strategies for freezing of gait and present a practical algorithm for the management of this disorder, based on a combination of evidence, when available, and clinical experience of the authors. Further research is needed to formally establish the merits of our proposed treatment protocol.
Copyright © 2015 Elsevier Ltd. All rights reserved.
Freezing of gait is a disabling symptom of Parkinson's disease that causes a paroxysmal cessation of normal footsteps while walking. Despite a great deal of empirical research, the pathophysiological mechanisms underlying the symptom remain unclear. In this targeted review, we synthesize recent insights from research into freezing in an effort to clarify the neurobiological basis of this phenomenon. We conclude that freezing manifests via a common neural pathway in which transient increases in inhibitory basal ganglia output lead to decreased activity within the brainstem structures that coordinate gait. This cascade may be triggered through dopaminergic depletion in the striatum and over-activity within the subthalamic nucleus. These insights may benefit both the diagnostic and therapeutic management of freezing in Parkinson's disease.
Freezing of Gait (FOG) is a disabling motor symptom experienced by a large proportion of patients with Parkinson's disease (PD). Whilst it is known that FOG contributes to lower health-related quality of life (HRQoL), previous studies have not accounted for other important factors when measuring the specific impact of this symptom. The aim of this study was to examine FOG and HRQoL whilst controlling for other factors that are known to impact patient wellbeing, including cognition, motor severity, sleep disturbance and mood. Two hundred and three patients with idiopathic PD (86 with FOG) were included in the study. All patients were between Hoehn & Yahr stages I-III. A forced entry multiple regression model evaluating the relative contribution of all symptoms was conducted, controlling for time since diagnosis and current dopaminergic treatment. Entering all significantly correlated variables into the regression model accounted for the majority of variance exploring HRQoL. Self-reported sleep-wake disturbances, depressive and anxious symptoms and FOG were individually significant predictors. FOG accounted for the highest amount of unique variance. Whilst sleep-wake disturbance and mood have a significant negative impact on HRQoL in PD, the emergence of FOG represents the most substantial predictor amongst patients in the earlier clinical stages of disease. This finding presumably reflects the disabling loss of independence and fear of injury associated with FOG and underlines the importance of efforts to reduce this common symptom.
Freezing of gait (FoG) is a transient inability to initiate or maintain stepping that often accompanies advanced Parkinson's disease (PD) and significantly impairs mobility. The current study uses a multimodal neuroimaging approach to assess differences in the functional and structural locomotor neural network in PD patients with and without FoG and relates these findings to measures of FoG severity. Twenty-six PD patients and fifteen age-matched controls underwent resting-state functional magnetic resonance imaging and diffusion tensor imaging along with self-reported and clinical assessments of FoG. After stringent movement correction, fifteen PD patients and fourteen control participants were available for analysis. We assessed functional connectivity strength between the supplementary motor area (SMA) and the following locomotor hubs: 1) subthalamic nucleus (STN), 2) mesencephalic and 3) cerebellar locomotor region (MLR and CLR, respectively) within each hemisphere. Additionally, we quantified structural connectivity strength between locomotor hubs and assessed relationships with metrics of FoG. FoG+ patients showed greater functional connectivity between the SMA and bilateral MLR and between the SMA and left CLR compared to both FoG- and controls. Importantly, greater functional connectivity between the SMA and MLR was positively correlated with i) clinical, ii) self-reported and iii) objective ratings of freezing severity in FoG+, potentially reflecting a maladaptive neural compensation. The current findings demonstrate a re-organization of functional communication within the locomotor network in FoG+ patients whereby the higher-order motor cortex (SMA) responsible for gait initiation communicates with the MLR and CLR to a greater extent than in FoG- patients and controls. The observed pattern of altered connectivity in FoG+ may indicate a failed attempt by the CNS to compensate for the loss of connectivity between the STN and SMA and may reflect a loss of lower-order, automatic control of gait by the basal ganglia.
Freezing of gait is one of the most debilitating symptoms in Parkinson's disease as it causes falls and reduces mobility and quality of life. The pedunculopontine nucleus is one of the major nuclei of the mesencephalic locomotor region and has neurons related to anticipatory postural adjustments preceding step initiation as well as to the step itself, thus it may be critical for coupling posture and gait to avoid freezing. Because freezing of gait and postural impairments have been related to frontal lesions and frontal dysfunction such as executive function, we hypothesized that freezing is associated with disrupted connectivity between midbrain locomotor regions and medial frontal cortex. We used diffusion tensor imaging to quantify structural connectivity of the pedunculopontine nucleus in patients with Parkinson's disease with freezing of gait, without freezing, and healthy age-matched controls. We also included behavioural tasks to gauge severity of freezing of gait, quantify gait metrics, and assess executive cognitive functions to determine whether between-group differences in executive dysfunction were related to pedunculopontine nucleus structural network connectivity. Using seed regions from the pedunculopontine nucleus, we were able to delineate white matter connections between the spinal cord, cerebellum, pedunculopontine nucleus, subcortical and frontal/prefrontal cortical regions. The current study is the first to demonstrate differences in structural connectivity of the identified locomotor pathway in patients with freezing of gait. We report reduced connectivity of the pedunculopontine nucleus with the cerebellum, thalamus and multiple regions of the frontal cortex. Moreover, these structural differences were observed solely in the right hemisphere of patients with freezing of gait. Finally, we show that the more left hemisphere-lateralized the pedunculopontine nucleus tract volume, the poorer the performance on cognitive tasks requiring the initiation of appropriate actions and/or the inhibition of inappropriate actions, specifically within patients with freezing. These results support the notion that freezing of gait is strongly related to structural deficits in the right hemisphere's locomotor network involving prefrontal cortical areas involved in executive inhibition function.
Freezing of gait (FOG) is defined as a brief, episodic absence or marked reduction of forward progression of the feet despite the intention to walk. It is one of the most debilitating motor symptoms in patients with Parkinson's disease (PD) as it may lead to falls and a loss of independence. The pathophysiology of FOG seems to differ from the cardinal features of PD and is still largely unknown. In the present paper, we review the studies that were performed since 2011 on methods to provoke and assess FOG and discuss new insights into behavioral and neural mechanisms underlying this clinical phenomenon. We conclude that most of the work reviewed confirms that gait pattern generation disturbances are central to FOG. The finding that FOG reflects a combined motor and cognitive de-automatization deficit, which may not be sufficiently offset by executive control, probably acts as parallel mechanism.
We have previously published a technique for objective assessment of freezing of gait (FOG) in Parkinson's disease (PD) from a single shank-mounted accelerometer. Here we extend this approach to evaluate the optimal configuration of sensor placement and signal processing parameters using seven sensors attached to the lumbar back, thighs, shanks and feet.
Multi-segmental acceleration data was obtained from 25 PD patients performing 134 timed up and go tasks, and clinical assessment of FOG was performed by two experienced raters from video. Four metrics were used to compare objective and clinical measures; the intraclass correlation coefficient (ICC) for number of FOG episodes and the percent time frozen per trial; and the sensitivity and specificity of FOG detection.
The seven-sensor configuration was the most robust, scoring highly on all measures of performance (ICC number of FOG 0.75; ICC percent time frozen 0.80; sensitivity 84.3%; specificity 78.4%). A simpler single-shank sensor approach provided similar ICC values and exhibited a high sensitivity to FOG events, but specificity was lower at 66.7%. Recordings from the lumbar sensor offered only moderate agreement with the clinical raters in terms of absolute number and duration of FOG events (likely due to musculoskeletal attenuation of lower-limb 'trembling' during FOG), but demonstrated a high sensitivity (86.2%) and specificity (82.4%) when considered as a binary test for the presence/absence of FOG within a single trial.
The seven-sensor approach was the most accurate method for quantifying FOG, and is best suited to demanding research applications. A single shank sensor provided measures comparable to the seven-sensor approach but is relatively straightforward in execution, facilitating clinical use. A single lumbar sensor may provide a simple means of objective FOG detection given the ubiquitous nature of accelerometers in mobile telephones and other belt-worn devices.
Over half of patients with PD eventually develop freezing of gait (FoG), an intermittent failure to initiate or maintain walking that is often associated with trembling of the legs. We tested 21 PD with FoG, 27 PD without FoG, and 21 healthy elderly people in a clinic with the Intrumented Timed Up and Go test (ITUG). FoG was quantified from the power spectral density of the antero-posterior shank acceleration from which a Frequency Ratio was calculated as the square of the total power in the 3-8 Hz band, divided by the square of the total power in the .5-3 Hz band. Spatiotemporal gait parameters calculated from synchronized gyroscopes on the two legs were also measured in these subjects. The Frequency Ratio was significantly larger in freezers than in non-freezers or control subjects. It better differentiated gait disorders between PD subjects with and without FoG than traditional gait measures such as stride length, stride velocity and double support time. The Frequency Ratio was validated as significantly correlated with self-perceived severity of gait and balance confidence. This Freezing Ratio will be useful to quantify FoG during a simple ITUG, a popular clinical test of mobility.
After 20 years follow-up of newly diagnosed patients with Parkinson's disease (PD), 100 of 136 (74%) have died. The mortality rate fell in the first 3 years of treatment, then rose compared to the general population, the standardized mortality ratio from 15 to 20 years reaching 3.1. Drug induced dyskinesia and end of dose failure were experienced by most patients, but the main current problems relate to the non-levodopa responsive features of the disease. Dementia is present in 83% of 20-year survivors. Dementia correlates with increasing age and probably reflects an interplay of multiple pathologies. Seventeen people with dementia had postmortems. Eight had diffuse Lewy bodies as the only cause of dementia, while others had mixed neuropathology. Only one person lives independently and 48% are in nursing homes. Excessive daytime sleepiness is noted in 70%, falls have occurred in 87%, freezing in 81%, fractures in 35%, symptomatic postural hypotension in 48%, urinary incontinence in 71%, moderate dysarthria in 81%, choking in 48%, and hallucinations in 74%. The challenge is to understand the cellular mechanisms underlying the diverse features of advanced PD that go far beyond a lack of dopamine. © 2008 Movement Disorder Society
In this paper, we present a wearable assistant for Parkinson's disease (PD) patients with the freezing of gait (FOG) symptom. This wearable system uses on-body acceleration sensors to measure the patients' movements. It automatically detects FOG by analyzing frequency components inherent in these movements. When FOG is detected, the assistant provides a rhythmic auditory signal that stimulates the patient to resume walking. Ten PD patients tested the system while performing several walking tasks in the laboratory. More than 8 h of data were recorded. Eight patients experienced FOG during the study, and 237 FOG events were identified by professional physiotherapists in a post hoc video analysis. Our wearable assistant was able to provide online assistive feedback for PD patients when they experienced FOG. The system detected FOG events online with a sensitivity of 73.1% and a specificity of 81.6%. The majority of patients indicated that the context-aware automatic cueing was beneficial to them. Finally, we characterize the system performance with respect to the walking style, the sensor placement, and the dominant algorithm parameters.
Parkinson's disease (PD) is a neurodegenerative disorder resulting in motor disturbances that can impact normal gait. Although PD initially responds well to pharmacological treatment, as the disease progresses efficacy often fluctuates over the course of the day, and clinical management would benefit from long-term objective measures of gait. We have previously described a small device worn on the shank that uses acceleration and angular velocity sensors to calculate stride length and identify freezing of gait in PD patients. In this study we extend validation of the gait monitor to 24-h using simultaneous video observation of PD patients.
A sleep laboratory was adapted to perform 24-hr video monitoring of patients while wearing the device. Continuous video monitoring of a sleep lab, hallway, kitchen and conference room was performed using a 4-camera security system and recorded to hard disk. Subjects (3) wore the gait monitor on the left shank (just above the ankle) for a 24-h period beginning around 5 pm in the evening. Accuracy of stride length measures were assessed at the beginning and end of the 24-h epoch. Two independent observers rated the video logs to identify when subjects were walking or lying down.
The mean error in stride length at the start of recording was 0.05 m (SD 0) and at the conclusion of the 24 h epoch was 0.06 m (SD 0.026). There was full agreement between observer coding of the video logs and the output from the gait monitor software; that is, for every video observation of the subject walking there was a corresponding pulse in the monitor data that indicated gait.
The accuracy of ambulatory stride length measurement was maintained over the 24-h period, and there was 100% agreement between the autonomous detection of locomotion by the gait monitor and video observation.
The Timed Up and Go (TUG) test has been used to assess balance and mobility in Parkinson's Disease (PD). However, it is not known if this test is sensitive to subtle abnormalities present in early stages of the disease, when balance and gait problems are not clinically evident but may be detected with instrumented analysis of movement. We hypothesise that postural transitions and arm swing during gait will be the most sensitive characteristics of the TUG for early PD. In the present study, we instrumented the TUG test (iTUG) using portable inertial sensors, and extended the walking distance from 3 m (traditional TUG) to 7 m. Twelve subjects with early-to-moderate, untreated PD and 12 healthy individuals participated. Our findings show that although the stopwatch measure of TUG duration did not detect any abnormalities in early-to-mid-stage PD, the peak arm swing velocity on the more affected side, average turning velocity, cadence and peak trunk rotation velocity were significantly slower. These iTUG parameters were also correlated with the Unified Parkinson's Disease Rating Motor Scale. Thus, the iTUG test is sensitive to untreated PD and could potentially detect progression of PD and response to symptomatic and disease-modifying treatments.
Freezing in Parkinson's disease is a severe and disabling problem of unknown aetiology. The aim of this study was to analyse the temporal pattern and the magnitude of the electromyographic activity of the lower limb muscles just before freezing and to compare this with a voluntary stop and ongoing gait. We recruited 11 patients with a mean age of 64.8 years (SD 5.1) and a mean Unified Parkinson Disease Rating Scale (part III--off) score of 29 (SD 7.9). Within a standard 3D gait laboratory setting, surface electromyographic (EMG) data of the tibialis anterior (TA) and gastrocnemius (GS) muscles were collected using a portable EMG module. Patients in the off-phase of the medication cycle performed several trials of normal walking and voluntary stops or were exposed to freezing-provoking circumstances. Filtered EMG signals were rectified, smoothed and expressed as a percentage of the gait cycle. EMG onset was determined using a preset threshold, corrected after visual inspection. The magnitude of EMG was calculated by integrating EMG signals (iEMG) over (real) time. To control for the altered timing of activity, iEMG was also normalized for time (iEMGnormt). Analysis of variance of repeated measures analysis showed that significantly abnormal timing occurred in the TA and GS muscles with overall preserved reciprocity. Before freezing, TA swing activity already started prematurely during the pre-swing phase, whereas it was significantly shortened during the actual swing phase. For the GS muscle, a similar pattern of premature activation and termination was found during the stance phase before a freeze. GS activity also showed prolonged bursts of activity during the swing phase, not present during the normal and stop condition. Total iEMG activity of both TA and GS was significantly reduced during the pre-freezing gait cycles. However, when controlling for the altered duration of the bursts, the average iEMGnormt increased, as did the peak EMG in TA. In GS, iEMGnormt was not different in the three conditions. In conclusion, our data show that a consistent pattern of premature timing of TA and GS activity occurred before freezing, which was interpreted as a disturbance of central gait cycle timing. The total amount of EMG activity was reduced in both lower limb muscles due to the shortened time in which the muscles were active. In contrast to GS, activity in TA showed increased amplitudes of the EMG bursts, indicating a compensation strategy of pulling the leg into swing. The observed changes contribute to insufficient forward progression, deceleration and eventually a breakdown of movement.
Freezing of gait (FOG) is a common and debilitating, but largely mysterious, symptom of Parkinson's disease. In this review, we will discuss the cerebral substrate of FOG focusing on brain physiology and animal models. Walking is a combination of automatic movement processes, afferent information processing and intentional adjustments. Thus, normal gait requires a delicate balance between various interacting neuronal systems. To further understand gait control and specifically FOG, we will discuss the basic physiology of gait, animal models of gait disturbance including FOG, alternative etiologies of FOG and functional magnetic resonance studies investigating FOG. The outcome of these studies point to a dynamic network of cortical areas such as the supplementary motor area, as well as subcortical areas such as the striatum and the mesencephalic locomotor region (MLR) including the pedunculopontine nucleus (PPN). Additionally, we will review PPN (area) stimulation as a possible treatment for FOG, and ponder whether PPN stimulation truly is the right step forward. This article is protected by copyright. All rights reserved.
Background:
Despite the strong relationship between freezing of gait (FOG) and turning in Parkinson's disease (PD), few studies have addressed specific postural characteristics during turning that might contribute to freezing.
Methods:
Thirty participants with PD (16 freezers, 14 non-freezers) (all tested OFF medication) and 14 healthy controls walked 5 meters and turned 180° in a 3D gait laboratory. COM behavior was analyzed during four turning quadrants of 40° between 10° and 170° pelvic rotation and during 40° before actual FOG episodes. These pre-FOG segments were compared with similar turning sections in turns of freezers without FOG. Outcome parameters were turn time, COM distance, COM velocity, step width and the medial- and anterior COM position.
Results:
Turn time was increased in freezers compared to non-freezers (p=.000). No differences were found regarding COM distance and velocity during turning quadrants between groups and between freezers' pre-FOG segments and similar turning segments without FOG. Medial COM deviation was reduced in PD patients compared to controls (p=.004), but no differences were found between freezers and non-freezers. In turns with freezing, turn time increased (p=.005) and step width decreased (p=.025) pre-FOG. Freezers also showed a less medial (p=.020) and more anterior (p=.016) COM position pre-FOG compared to turning sections without FOG.
Conclusions:
Our results revealed no subgroup differences in COM behavior during uninterrupted turning. However, we found a reduced medial deviation, a forward COM shift and a decreased step width in freezers just before FOG episodes. These abnormalities may play a causal role, as they could hamper stability and fluent weight shifting necessary for continued stepping during turning.
Freezing of gait is a paroxysmal phenomenon that is frequently reported by the parkinsonian patients or their entourage. The phenomenon significantly alters quality of life but is often difficult to characterize in the physician's office. In the present review, we focus on the clinical characterization and quantification of freezing of gait. Various biomechanical methods (based mainly on time-frequency analysis) can be used to determine time-domain characteristics of freezing of gait. Methods already used to study non-gait freezing of other effectors (the lower limbs, upper limbs and orofacial area) are also being developed for the analysis of freezing in functional magnetic resonance imaging protocols. Here, we review the reliability of these methods and compare them with reliability of information obtained from physical examination and detailed analysis of the patient's medical history.
Importance
Freezing of gait (FOG) is a common axial symptom of Parkinson disease (PD).Objective
To determine the prevalence of FOG in a large group of PD patients, assess its relationship with quality of life and clinical and pharmacological factors, and explore its changes from the off to on conditions in patients with motor fluctuations.Design, Setting, and Participants
Cross-sectional survey of 683 patients with idiopathic PD. Scores for FOG were missing in 11 patients who were not included in the analysis. Patients were recruited from referral centers and general neurology clinics in public or private institutions in France.Exposure
Patients with FOG were identified as those with a score of 1 or greater on item 14 of the Unified Parkinson’s Disease Rating Scale (UPDRS) in the on condition. Item 14 scores for FOG in the off condition were also collected in patients with fluctuating motor symptoms.Main Outcomes and Measures
Quality of life (measured by the 39-item Parkinson’s Disease Questionnaire and 36-Item Short Form Health Survey), anxiety and depression (Hospital Anxiety and Depression Scale), clinical features (UPDRS), and drug consumption.Results
Of 672 PD patients, 257 reported FOG during the onstate (38.2%), which was significantly related to lower quality of life scores (P < .01). Freezing of gait was also correlated with longer PD duration (odds ratio, 1.92 [95% CI, 1.28-2.86]), higher UPDRS parts II and III scores (4.67 [3.21-6.78]), the presence of apathy (UPDRS item 4) (1.94 [1.33-2.82]), a higher levodopa equivalent daily dose (1.63 [1.09-2.43]), and more frequent exposure to antimuscarinics (3.07 [1.35-6.97]) (logistic regression). The FOG score improved from the off to on states in 148 of 174 patients with motor fluctuations (85.1%) and showed no change in 13.8%. The FOG score improved by more than 50% in 43.7% of patients. Greater improvement in the on state was observed in younger patients (r = −0.25; P < .01) with lower UPDRS II and III scores (r = −0.50; P < .01) and no antimuscarinic use (r = −0.21; P < .01).Conclusions and Relevance
Freezing of gait in PD patients correlates with poor quality of life, disease severity, apathy, and exposure to antimuscarinics. Dopaminergic therapy improved FOG in most patients with motor fluctuations, especially younger ones with less severe disease and no antimuscarinic use. This finding suggests that quality of life is impaired in PD patients with FOG and that optimizing dopaminergic therapy and avoiding antimuscarinics should be considered.
Objective
Impaired gait initiation (GI) in patients with advanced Parkinson’s disease (PD) is a typical functional sign of akinesia. Failure to initiate the first step is frequently presented by patients with freezing of gait (FOG) and is often considered as a subtype of freezing. The literature on the effects of cueing of GI preparation and execution remains controversial. Our objective was to establish whether auditory cueing improves the preparation and/or execution of GI in PD patients with a history of FOG.
Methods
We recorded first-step preparation and execution in 30 PD patients with confirmed FOG under two randomized conditions: self-triggered gait and gait cued by a sound beep in off and on-dopa conditions. Anticipatory postural adjustments (APAs) were evaluated by monitoring the trajectory of the centre of pressure.
Results
We compared the patients with 30 patients without history of FOG and 30 healthy controls (HCs). L-dopa only slightly improved characteristics of APAs in freezers but was effective to improve gait hypokinesia. Auditory cueing was effective in improving step preparation in freezers, who showed adequate APAs more frequently. As seen with HCs and patients without FOG, patients released their APAs quicker when auditory cueing was applied. However, cueing did not have a significant effect on step length. Clinically, auditory cueing also improved start hesitation in freezers.
Conclusions
Auditory cueing improved step preparation but not step execution in PD patients.
Significance
A failure to link step preparation and execution during GI may explain the poor first step execution seen in PD freezers.
Successful locomotion depends on postural control to establish and maintain appropriate postural orientation of body segments relative to one another and to the environment and to ensure dynamic stability of the moving body. This article provides a framework for considering dynamic postural control, highlighting the importance of coordination, consistency, and challenges to postural control posed by various locomotor tasks, such as turning and backward walking. The impacts of aging and various movement disorders on postural control are discussed broadly in an effort to provide a general overview of the field and recommendations for assessment of dynamic postural control across different populations in both clinical and research settings. Suggestions for future research on dynamic postural control during locomotion also are provided and include discussion of opportunities afforded by new and developing technologies, the need for long-term monitoring of locomotor performance in everyday activities, gaps in our knowledge of how targeted intervention approaches modify dynamic postural control, and the relative paucity of literature regarding dynamic postural control in movement disorder populations other than Parkinson's disease. © 2013 International Parkinson and Movement Disorder Society.
Background:
Turning is the most important trigger for freezing of gait (FOG) in Parkinson's disease (PD), and dual-tasking has been suggested to influence FOG as well.
Objective:
To understand the effects of dual tasking and turning on FOG.
Methods:
14 Freezers and 14 non-freezers matched for disease severity and 14 age-matched controls were asked to turn 180° and 360° with and without a cognitive dual-task during the off-period of the medication cycle. Total number of steps, duration, cadence, freezing-frequency, and secondary-task performance were measured.
Results:
Seven freezers froze during the protocol. Freezing occurred in 37.5% of trials during 180° turning compared to 0% during straight-line walking (X(2) = 10.44, p < 0.01). The occurrence of FOG increased during 360° when also a dual-task was added (X(2) = 4.23, p = 0.04). Freezers took significantly more steps and were slower than controls in all conditions. The presence of a dual-task increased these differences. Cadence increased significantly for freezers during 360° and 180° compared to straight-line walking. In contrast, cadence was decreased during turning in controls and non-freezers. During straight-line walking, only freezers made errors in the secondary task. Controls increased their error-rate during 180° turning, whereas freezers deteriorated their secondary task performance during 360°.
Conclusions:
360° turning in combination with a dual-task is the most important trigger for freezing. During turning, non-freezers and controls decreased their cadence whereas freezers increased it, which may be related to FOG. Freezers adopted a posture second strategy in contrast to non-freezers when confronted with a dual task.
Freezing and festination during gait are common yet poorly understood motor control deficits in people with Parkinson's disease (PD). As a basis for evidence based clinical decision making during rehabilitation, we explore the underlying factors associated with freezing of gait in PD. It is argued that disorders of motor set and the sequence effect (festination) are associated with freezing, either in isolation or in combination. The contribution of environmental constraints, task related factors, attention, mental status, and prolonged use of PD medications are also investigated. On the basis of these findings, we propose strategies to reduce the frequency and severity of freezing episodes for a range of locomotion tasks. © 2008 Movement Disorder Society
